Thermoplastic Polyolefin Blends

ABSTRACT

This invention relates to a blend composition comprising: 1) a linear ethylene containing polymer, such as a LLDPE, a HDPE or the like; and at least 1 weight percent of an in-reactor polymer blend comprising: (a) a first ethylene containing polymer having a density of greater than 0.90 g/cm 3  and a M w  of more than 20,000 g/mol; and (b) a second ethylene containing polymer having a density of less than 0.90 g/cm 3 , wherein the polymer blend has a T m  of at least 90° C. (DSC second melt), a density of less than 0.92 g/cm 3 , and the densities of the first and second polymers differ by at least 1%. Alternately the in-reactor polymer blend comprises: (a) a first ethylene polymer comprising 90 wt % to 100 wt % ethylene and from 0 wt % to less than 10 wt % comonomer, said first ethylene polymer component having density of greater than 0.920 g/cm 3 , an M w  of 20,000 g/mol or more; and (b) a second ethylene polymer comprising from 70 wt % to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, said second ethylene polymer having a density of 0.910 g/cm 3  or less, wherein the in-reactor polymer blend has one or more of the following characteristics: (a) at least 78 wt % ethylene; (b) a T m  of at least 100° C. over a density ranging from 0.84 to 0.92 g/cm 3 ; (c) a elongation at break of 300% or more; (d) a strain hardening ratio M300/M100 of at least 1.2; (e) a ratio of complex viscosity at 0.01 rad/s to the complex viscosity at 100 rad/s of at least 30; and (f) a shear thinning index of less than −0.2.

PRIORITY

This application is a continuation in part of U.S. Ser. No. 12/638,916,filed Dec. 15, 2009, which is a continuation in part of U.S. Ser. No.12/335,252, filed Dec. 15, 2008.

FIELD OF THE INVENTION

This invention relates to the blend compositions comprising a linearethylene containing polymer and an in-reactor polymer blend comprisingtwo ethylene containing polymers having different comonomer contents.

BACKGROUND OF THE INVENTION

Various types of polyethylene are used in the art. Low densitypolyethylene (“LDPE”) can be prepared at high pressure using freeradical initiators, and typically has a density in the range of0.916-0.940 g/cm³. LDPE is also known as “branched” or “heterogeneouslybranched” polyethylene because of the relatively high level of longchain branches extending from the main polymer backbone. Polyethylene inthe same density range, i.e., 0.916 to 0.940 g/cm³, which is linear anddoes not contain long chain branching, is also available; this “linearlow density polyethylene” (“LLDPE”) can be produced with conventionalZiegler-Natta catalysts or with metallocene catalysts. Relatively higherdensity LDPE, typically in the range of 0.928 to 0.940 g/cm³, issometimes referred to as medium density polyethylene (“MDPE”). HDPE hasa density of greater than 0.940 g/cm³, and is generally prepared withZiegler-Natta catalysts. Very low density polyethylene (“VLDPE”) can beproduced by a number of different processes yielding polymers withdifferent properties, but can be generally described as polyethylenehaving a density less than 0.916 g/cm³, typically 0.890 to 0.915 g/cm³,or 0.900 to 0.915 g/cm³.

Plastomers are ethylene/alpha-olefin copolymers with compositions andphysical properties spanning the range between plastics and elastomers.Comonomer content typically ranges from 10 wt % to 30 wt % and densityranges from 0.910 to 0.860 g/cm³. Particularly useful plastomers areoften ultra-low-density ethylene copolymers made using metallocenecatalysts. The uniform comonomer insertion results in low-densityplastomer exhibiting both plastic and elastomeric behavior. Compared toLLDPE, plastomers are lower in density, tensile strength, flexuralmodulus, hardness, and melting point. They exhibit higher elongation andtoughness and are substantially higher in clarity, with very low hazevalues at lower densities.

Each product slate has unique properties and is used for specificapplications. For some applications individual polymers do not possessthe necessary combination of properties. For instance, LLDPE providesgood toughness and other desirable properties but these propertiesdecrease as the modulus (modulus is proportional to density forpolyethylene) of the LLDPE increases. Generally, selecting optimumperformance is a matter of trading off one property against another, forexample, increasing modulus decreases toughness.

Individual polyolefins having certain characteristics are often blendedtogether in the hope of combining the positive attributes of theindividual components. Typically the result is a blend which displays anaverage of the individual properties of the individual resins. Blendinghas been used to form polymer compositions having altered properties,such as melt index and various processability characteristics. Blendinghas also been used to form polymer compositions having propertiesenhanced for particular end uses. For example, polymer blends have beenused to form cast or extruded films with altered film properties, suchas toughness, tear resistance, shrink properties, and other desired filmcharacteristics. For example, U.S. Pat. No. 4,438,238 describes blendsfor extrusion processing, injection molding and films where acombination of two ethylene-α-olefin copolymers with differentdensities, intrinsic viscosities and number of short chain branching per1,000 carbon atoms is attributed with such physical properties. U.S.Pat. No. 4,461,873 describes ethylene polymer blends of a high molecularweight ethylene polymer, preferably a copolymer, and a low molecularweight ethylene polymer, preferably an ethylene homopolymer, forimproved film properties and environmental stress crack resistanceuseful in the manufacture of film or in blow molding techniques, theproduction of pipes and wire coating. EP 0 423 962 describes ethylenepolymer compositions particularly suitable for gas pipes said to haveimproved environmental stress cracking resistance comprising two or morekinds of ethylene polymers different in average molecular weight, atleast one of which is a high molecular weight ethylene polymer having anintrinsic viscosity of 4.5 to 10.0 dl/g in decalin at 135° C. and adensity of 0.910 to 0.930 g/cm³ and another of which is a low molecularweight ethylene polymer having an intrinsic viscosity of 0.5 to 2.0dl/g, as determined for the first polymer, and a density of 0.938 to0.970 g/cm³.

U.S. Pat. No. 5,082,902 describes blends of linear polyethylene forinjection and rotational molding said to have reduced crystallizationtimes with improved impact strength and environmental stress crackresistance. The blends comprise: (a) a first polymer having a density offrom 0.85 to 0.95 g/cm³ and an melt index of 1 to 200 g/10 min; and (b)a second polymer having a density of 0.015 to 0.15 g/cm³ greater thanthe density of the first polymer and an melt index differing by no morethat 50% from the melt index of the first polymer. U.S. Pat. No.5,306,775 describes polyethylene blends said to have a balance ofproperties for processing by any of the known thermoplastic processes,specifically including improved environmental stress crack resistance.These compositions have: (a) low molecular weight ethylene resins madeusing a chromium oxide based catalyst and having a density at least0.955 g/cm³ and melt index (MI) between 25 and 400 g/10 min; and (b)high molecular weight ethylene copolymer resins with a density nothigher than 0.955 g/cm³ and a high load melt index (HLMI) between 0.1and 50 g/10 min.

U.S. Pat. No. 5,382,631 describes linear interpolymer polyethyleneblends having narrow molecular weight distribution (M_(w)/M_(n)≦3)and/or composition distribution breadth index (CDBI) less than 50%,where the blends are generally free of fractions having higher molecularweight and lower average comonomer contents than other blend components.Improved properties for films, fibers, coatings, and molded articles areattributed to these blends. In one example, a first component is anethylene-butene copolymer with a density of 0.9042 g/cm³, M_(w)/M_(n) of2.3, and an MI of 4.0 dg/min and a second component is an HDPE with adensity of 0.9552 g/cm³, M_(w)/M_(n) of 2.8, and an MI of 5.0 dg/min.The blend is said to have improved tear strength characteristics.

U.S. Pat. No. 6,362,270 describes thermoplastic compositions said to beespecially suited to rotomolding applications comprising: (a) a majoritycomponent that may be an ethylene interpolymer having a density greaterthan 0.915 g/cm³ and preferably a melt index (MI) of from about 2 to 500dg/min; and (b) an impact additive that may be an ethylene interpolymerhaving a density less than 0.915 g/cm³ and an MI preferably greater than0.05 dg/min and less than 100 dg/min. Improved physical properties asascribed to these compositions include improved impact strength and goodenvironmental stress crack resistance.

Physical blends have problems of inadequate miscibility. Unless thecomponents are selected for their compatibility they can phase separateor smaller components can migrate to the surface. Reactor blends, alsocalled intimate blends (a composition comprising two or more polymersmade in the same reactor or in a series of reactors) are often used toaddress these issues; however, finding catalyst systems that willoperate under the same environments to produce different polymers hasbeen a challenge.

Multiple catalyst systems have been used in the past to produce reactorblends of various polymers and other polymer compositions. Reactorblends and other one-pot polymer compositions are often regarded assuperior to physical blends of similar polymers. For example U.S. Pat.No. 6,248,832 discloses a polymer composition produced in the presenceof one or more stereospecific metallocene catalyst systems and at leastone non-stereospecific metallocene catalyst system. The resultantpolymer has advantageous properties over the physical blends disclosedin EP 0 527 589 and U.S. Pat. No. 5,539,056.

Thus, there has been interest in the art in developing multiple catalystsystems to produce new polymer compositions. For example, U.S. Pat. No.6,147,180 discloses a thermoplastic elastomer composition comprising abranched olefin copolymer backbone and crystallizable side chains,wherein the copolymer has A) a T_(g) as measured by DSC less than orequal to 10° C.; B) a T_(m) greater than 80° C.; C) an elongation atbreak of greater than or equal to 300%; D) a tensile strength of greaterthan or equal to 1,500 psi (10.3 MPa) at 25° C.; and E) an elasticrecovery of greater than or equal to 50%. The thermoplastic elastomercomposition can be produced by A) polymerizing ethylene or propylene,optionally with one or more copolymerizable monomers, in apolymerization reaction under conditions sufficient to form a polymerhaving greater than 40% chain end-group unsaturation; and B)copolymerizing the product of A) with ethylene and one or morecopolymerizable monomers so as to prepare said branched olefincopolymer. The two polymerization steps can be conducted sequentially orconcurrently. Although the polymer exhibited good tensile properties andelastic recovery, the shear thinning was low. In addition U.S. Pat. No.6,323,284 discloses a method to produce thermoplastic compositions(mixtures of crystalline and amorphous polyolefin copolymers) bycopolymerizing alpha-olefins and alpha, omega dienes using two separatecatalyst systems.

Likewise, others have experimented with multiple stage processes toproduce new polymer compositions. For example, EP 0 366 411 discloses agraft polymer having an EPDM backbone with polypropylene grafted theretoat one or more of the diene monomer sites through the use of a two-stepprocess using a different Ziegler-Natta catalyst system in each step.This graft polymer is stated to be useful for improving the impactproperties in blended polypropylene compositions.

Although each of the polymers/blends described in the above referenceshas interesting combinations of properties, there remains a need for newcompositions that offer other new and different property balancestailored for a variety of end uses. In particular, it would be desirableto find a composition that contains cross products useful ascompatibilizer compounds for interfacial interactions.

Other references of interest include: U.S. Patent ApplicationPublication Nos. 2006/0281868; 2008/0027173; 2008/0033124; 2004/0054100;WO 2003/040201; U.S. Pat. Nos. 6,319,998; 6,284,833; 6,512,019;7,365,136; 6,441,111; 6,806,316; 5,962,595; 5,516,848; 6,147,180; EP 0527 589; and EP 0 749 992.

SUMMARY OF THE INVENTION

The present invention provides a polymer blend of a linear ethylenecontaining polymer, such as a LLDPE, a HDPE or the like, and anin-reactor polymer blend. The in-reactor polymer blend is a mixture of ahigher density polyethylene and a lower density polyethylene as well ascross product. This in-reactor polymer blend exhibits a uniquecombination of long elongation and strong shear thinning and is used asa modifier to a linear ethylene containing polymer, such as a LLDPE, aHDPE, or the like.

This invention discloses blend compositions of a linear ethylenecontaining polymer, such as a LLDPE, a HDPE, or the like, within-reactor polymer blends. The resulting blend compositions showimproved melt strength and shear thinning compared to the neat linearethylene containing polymer. These attributes will expand and enable theuse of this new blend composition in applications, such as films,thermoformed articles, extruded goods, etc. The in-reactor polymer blendused in this new blend composition can be prepared in a batch, acontinuous, or a semi-continuous reactor by a dual metallocene catalystsystem. Besides hexene, other α-olefin comonomer, such as propylene,butene, octene, etc., can be used.

This invention further relates to a composition comprising:

1) a linear ethylene containing polymer having a density of at least0.910 g/cm³; and

2) an in-reactor polymer blend comprising: (a) a first ethylenecontaining polymer having a density of greater than 0.90 g/cm³ and aM_(w) of more than 20,000 g/mol; and (b) a second ethylene containingpolymer having a density of less than 0.90 g/cm³, wherein the densitiesof the first and second polymers differ by at least 1%, and wherein thein-reactor polymer blend has a T_(m) of at least 90° C. (DSC secondmelt), a density of less than 0.92 g/cm³, and contains at least 78 wt %ethylene.

This invention further relates to a composition including a linearethylene containing polymer, such as a LLDPE, a HDPE or the like, and anin-reactor polymer blend. The linear ethylene containing polymer has adensity of greater than 0.910 g/cm³ and an M_(w) of more than 50,000g/mol. The in-reactor polymer blend comprises one or more of: (a) a highcrystalline ethylene polymer comprising 90 wt % to 100 wt % ethylene andfrom about 0 wt % to less than 10 wt % comonomer, said high crystallineethylene polymer component having density of greater than 0.920 g/cm³,an M_(w) of 20,000 g/mol or more and optionally a T_(m) of 110° C. ormore; and (b) a low crystalline ethylene polymer comprising from 70 wt %to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, said lowcrystalline ethylene polymer having a density of 0.910 g/cm³ or less sothat the in-reactor polymer blend contains at least 78 wt % ethylene.

This invention relates to a composition comprising:

a linear ethylene containing polymer having a density of at least 0.910g/cm³, such as a LLDPE, a HDPE, or the like; and

at least 1 weight percent of an in-reactor polymer blend comprising: (a)a high crystalline ethylene polymer comprising 90 wt % to 100 wt %ethylene and from 0 wt % to less than 10 wt % comonomer, said highcrystalline ethylene polymer component having density of greater than0.920 g/cm³, an M_(w) of 20,000 g/mol or more and optionally a T_(m) of110° C. or more; and (b) a low crystalline ethylene polymer comprisingfrom 70 wt % to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, saidlow crystalline ethylene polymer having a density of 0.910 g/cm³ orless, wherein the in-reactor polymer blend has one or more of thefollowing characteristics:

-   -   (a) at least 78 wt % ethylene;    -   (b) a T_(m) of at least 100° C. over a density ranging from 0.84        to 0.92 g/cm³;    -   (c) an elongation at break of 300% or more;    -   (d) a strain hardening ratio, M300/M100, of at least 1.2;    -   (e) a ratio of complex viscosity at 0.01 rad/s to the complex        viscosity at 100 rad/s of at least 30; and    -   (f) a shear thinning index of less than −0.2.

In this in-reactor polymer blend, the first ethylene polymer componentmay also be referred to as a “high crystallinity” ethylene polymercomponent, where “high” means the density is greater than 0.920 g/cm³.The second ethylene polymer component may also be referred to as a “lowcrystallinity” ethylene polymer component, where “low” means the densityis 0.910 g/cm³ or less.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphic illustration of the relationship between the complexviscosity and frequency for the in-reactor polymer blends produced inExamples 3 to 5 (measured at a temperature of 190° C.).

FIG. 2 is a plot of loss or phase angle vs. complex or dynamic modulus(G*) for the in-reactor polymer blends produced in Examples 3 to 5.

FIG. 3 shows stress-strain curves for the in-reactor polymer blendsproduced in Examples 3 to 5.

FIG. 4 shows TREF traces of dW/dT against elution temperature T for thein-reactor polymer blends produced in Examples 3 to 5, where W is theconcentration of eluted polymer.

FIG. 5 are crystallization analysis fractionation (CRYSTAF) traces forthe fractionated components of in-reactor polymer blend produced inExample 4.

FIG. 6 shows atomic force micrographs (AFM) of the in-reactor polymerblends produced in Example 3 (field of view=40×40 μm) and Example 5(field of view=10×10 μm).

FIG. 7 provides stress-strain curves of the in-reactor polymer blendsproduced in Examples 6 to 9.

FIG. 8 are van Gurp-Palmen plots of polymeric materials in Table 4.

FIG. 9 provides complex viscosity versus frequency plots of polymericmaterials in Table 4.

FIG. 10 are van Gurp-Palmen plots of polymeric materials in Table 5.

DETAILED DESCRIPTION

As used herein the term “in-reactor polymer blend” also referred to asan “intimate blend” is intended to mean a mixture of polymers producedin one or more polymerization zones in the same polymerizationprocess/system without the need for post polymerization blending(although the resultant copolymer can undergo post polymerizationblending, for example, to incorporate modifiers and additives). Eachpolymer component in the mixture possesses a unique molecular structuresuch as percent comonomer content, molecular weight and some of thecomponents have molecular architectures such as branched block products.

A polymerization zone is defined as an area where activated catalystsand monomers are contacted and a polymerization reaction takes place.When multiple reactors are used in either series or parallelconfiguration, each reactor is considered as a separate polymerizationzone. For a multi-stage polymerization in both a batch reactor and acontinuous reactor, each polymerization stage is considered as aseparate polymerization zone.

As used herein, the term continuous means a system that operates withoutinterruption or cessation. Hence, a continuous process is one wherethere is continuous addition to, and withdrawal of reactants andproducts from, the reactor system. Continuous processes can be operatedin steady state, i.e., the composition of effluent remains fixed withtime if the flow rate, temperature/pressure and feed composition remaininvariant. For example, a continuous process to produce a polymer wouldbe one where the reactants are continuously introduced into one or morereactors and polymer product is continuously withdrawn.

An “ethylene containing polymer” also referred to as an “ethylenepolymer” is a polymer having at least 50 wt % ethylene monomer (basedupon the weight of the polymer), with the balance being made up byhydrocarbon monomers, preferably C₃ to C₁₂ hydrocarbon monomers,preferably propylene, butene, hexene, octene, or mixtures thereof. A“linear ethylene containing polymer” also referred to as a “linearethylene polymer” is an ethylene containing polymer having a branchingindex (g′) of 0.98 or more, preferably 0.99 or more, preferably 1.0 (1.0being the theoretical limit of g′). Branching index (g′) is determinedas described in U.S. Patent Application Publication No. 2006/0173123,particularly pages 24-25. In the event there is a conflict between thesize exclusion chromatography method described in 2006/0173123 and thesize exclusion chromatography method described below, the methoddescribed in 2006/0173123 shall be used for determination of g′. A“metallocene polyethylene” or an “mPE” is an ethylene polymer having aCDBI of greater than 50%, preferably greater than 60%. An “mLLDPE” is anethylene polymer (preferably a copolymer) having a CDBI of greater than50% (preferably greater than 60%) and a density of 0.910 to 0.940 g/cm³.For purposes of this specification and the claims appended thereto, whena polymer or copolymer is referred to as comprising an olefin,including, but not limited to ethylene, propylene, and butene, theolefin present in such polymer or copolymer is the polymerized form ofthe olefin. For example, when a copolymer is said to have an “ethylene”content of 35 wt % to 55 wt %, it is understood that the mer unit in thecopolymer is derived from ethylene in the polymerization reaction andsaid derived units are present at 35 wt % to 55 wt %, based upon theweight of the copolymer.

For purposes of this invention and the claims thereto: 1) an ethylenepolymer having a density of 0.86 g/cm³ or less is referred to as anethylene elastomer or elastomer; 2) an ethylene polymer having a densityof more than 0.86 to less than 0.910 g/cm³ is referred to as an ethyleneplastomer or plastomer; 3) an ethylene polymer having a density of 0.910to 0.940 g/cm³ is referred to as a low density polyethylene or “LDPE”(Low density polyethylene includes both LDPE and LLDPE unless otherwisenoted); 4) a linear ethylene polymer having a density of 0.910 to 0.940g/cm³ is referred to as a linear low density polyethylene or “LLDPE”(LLDPE is typically made using conventional Ziegler-Natta or metallocenecatalysts); and 5) an ethylene polymer having a density of more than0.940 g/cm³ is referred to as a high density polyethylene or “HDPE”. Forthese definitions, and for this invention and the claims thereto,density is determined using a density-gradient column, as described inASTM D1505, on a compression-molded specimen that has been slowly cooledto room temperature (i.e., over a period of 10 minutes or more) andallowed to age for a sufficient time that the density is constant within+/−0.001 g/cm³.

This invention relates to a composition comprising:

1) 0.5 wt % to 99 wt % (preferably 50 wt % to 99 wt %, preferably 85 wt% to 99 wt %) of a linear ethylene containing polymer having a densityof at least 0.910 g/cm³; and

2) 99.5 wt % to 1 wt % (preferably 50 wt % to 1 wt %, preferably 15 wt %to 1 wt %) of an in-reactor polymer blend, based upon the weight of thecomposition, preferably where the in-reactor polymer blend comprises:(a) a first ethylene containing polymer having a density of greater than0.90 g/cm³ and an M_(w) of more than 20,000 g/mol; and (b) a secondethylene containing polymer having a density of less than 0.90 g/cm³,wherein the densities of the first and second polymers differ by atleast 1%, and wherein the in-reactor polymer blend has a T_(m) of atleast 90° C. (DSC second melt), a density of less than 0.92 g/cm³, andcontains at least 78 wt % ethylene.

This invention further relates to a composition including a linearethylene containing polymer, such as a LLDPE, a HDPE or the like, and anin-reactor polymer blend. The linear ethylene containing polymer has adensity of greater than 0.910 g/cm³ and an M_(w) of more than 50,000g/mol. The in-reactor polymer blend comprises one or more of: (a) a highcrystalline ethylene polymer comprising 90 wt % to 100 wt % ethylene andfrom about 0 wt % to less than 10 wt % comonomer, said high crystallineethylene polymer component having density of greater than 0.920 g/cm³,an M_(w) of 20,000 g/mol or more and optionally a T_(m) of 110° C. ormore; and (b) a low crystalline ethylene polymer comprising from 70 wt %to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, said lowcrystalline ethylene polymer having a density of 0.910 g/cm³ or less sothat the in-reactor polymer blend contains at least 78 wt % ethylene.

This invention also relates to a composition comprising:

1) a linear ethylene containing polymer having a density of at least0.910 g/cm³, such as a LLDPE, a HDPE, or the like; and

2) at least 1 wt % of an in-reactor polymer blend comprising: (a) a highcrystalline ethylene polymer comprising 90 wt % to 100 wt % ethylene andfrom 0 wt % to less than 10 wt % comonomer, said high crystallineethylene polymer component having density of greater than 0.920 g/cm³,an M_(w) of 20,000 g/mol or more and optionally a T_(m) of 110° C. ormore; and (b) a low crystalline ethylene polymer comprising from 70 wt %to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, said lowcrystalline ethylene polymer having a density of 0.910 g/cm³ or less,wherein the in-reactor polymer blend has one or more of the followingcharacteristics:

-   -   (a) at least 78 wt % ethylene;    -   (b) a T_(m) of at least 100° C. over a density ranging from 0.84        to 0.92 g/cm³;    -   (c) an elongation at break of 300% or more;    -   (d) a strain hardening ratio, M300/M100, of at least 1.2;    -   (e) a ratio of complex viscosity at 0.01 rad/s to the complex        viscosity at 100 rad/s of at least 30; and    -   (f) a shear thinning index of less than −0.2.

Linear Ethylene Containing Polymers

This invention relates to a composition comprising a linearethylene-containing polymer and an in-reactor blend. The linearethylene-containing polymers are generally polymers having a density of0.910 g/cm³ or more and include HDPE and LLDPE produced either withconventional Ziegler-Natta catalysts or with metallocene catalysts.

In a preferred embodiment, the linear ethylene containing polymer is apolymer having a density of 0.910 g/cm³ or more; an M_(w) of 50,000g/mol or more (preferably 75,000 g/mol or more, preferably 100,000 g/molor more); a g′ of 0.95 or more (preferably 0.98 or more, preferably 0.99or more, preferably 1.0); an M_(w)/M_(n) of greater than 1 to 10(preferably from 1.5 to 8, preferably 2 to 5); and comprises from 50mole % to 100 mole % ethylene (preferably 65 mole % to 99 mole %,preferably 80 mole % to 97 mole %, preferably 90 mole % to 97 mole %),and from 0 to 50 mole % (preferably from 1 to 35 mole %, preferably 3 to20 mole %, preferably 3 mole % to 10 mole %) of C₂ to C₄₀ comonomer(preferably C₂ to C₄₀ alpha-olefin, preferably a C₅ to C₄₀ alpha olefin,preferably propylene, butene, pentene, hexene, or octene).

In a preferred embodiment, the ethylene containing polymer has anextractables level of less than 2.6 wt %, as defined in 21 CFR177.1520(d)(3)(ii).

In a preferred embodiment, the ethylene polymers are metallocenepolyethylenes (mPE's). The mPE homopolymers or mPE copolymers (such asmLLDPE) may be produced using mono- or bis-cyclopentadienyl transitionmetal catalysts or other metallocene catalysts in combination with anactivator of alumoxane and/or a non-coordinating anion in solution,slurry, high pressure, or gas phase. The catalyst and activator may besupported or unsupported and the cyclopentadienyl rings may besubstituted or unsubstituted. The mPE polymers, particularly mLLDPEcopolymers, can include those containing a small amount of long chainbranching (LCB), for example below 5 wt %. Several commercial productsproduced with such catalyst/activator combinations are commerciallyavailable from ExxonMobil Chemical Company in Baytown, Tex. under thetradenames EXCEED™ and ENABLE™.

In a particularly preferred embodiment, the compositions of thisinvention comprise a linear ethylene containing polymer that is ametallocene LLDPE (mLLDPE), preferably present at 0.5 wt % to 99 wt % ofan mLLDPE, more preferably 50 wt % to 99 wt %, more preferably 90 wt %to 99 wt %, based upon the weight of the composition. Preferred mLLDPEsare copolymers comprising at least 50 wt % ethylene and having up to 50wt %, preferably 1 wt % to 35 wt %, even more preferably 1 wt % to 6 wt% of a C₃-C₂₀ comonomer (e.g., C₄, C₆, C₈), based upon the weight of thecopolymer. The polyethylene copolymers preferably have an M_(w)/M_(n) offrom greater than 1 to 10, preferably from 1.5 to 8, preferably 2 to 7,preferably from 2 to 5. The polyethylene copolymers preferably have acomposition distribution breadth index (CDBI) of 60% to 85%, preferably65% to 85%. In another preferred embodiment the ethylene copolymer has adensity of 0.910 to 0.935 g/cm³ and a CDBI of 60% to 85% or more,preferably between 65% and 85%. Composition Distribution Breadth Index(CDBI) is a measure of the composition distribution of monomer withinthe polymer chains and is measured by the procedure described in PCTpublication WO 93/03093, published Feb. 18, 1993 including thatfractions having a weight average molecular weight (M_(w)) below 15,000g/mol are ignored when determining CDBI. For purposes of this inventiona homopolymer is defined to have a CDBI of 100%.

In another embodiment the linear ethylene containing polymer is apolymer of an ethylene and at least one alpha olefin. The alpha olefinhas 5 to 20 carbon atoms, more preferably 5 to 10 carbon atoms and mostpreferably 5 to 8 carbon atoms. The polymer is obtainable by acontinuous gas phase polymerization using supported catalyst of anactivated molecularly discrete catalyst in the substantial absence of analuminum alkyl based scavenger (e.g., triethylaluminum (TEAL),trimethylaluminum (TMAL), triisobutyl aluminum (TIBAL),tri-n-hexylaluminum (TNHAL) and the like). The polymer has a melt index,MI, (ASTM D1238, 190° C./2.16 kg) of from 0.1 to 15 (preferably 0.3 to10); a CDBI of at least 70% (preferably at least 75%), a density of from0.910 to 0.930 g/cm³ (preferably from 0.915 to 0.927 g/cm³); a hazevalue (ASTM D 1003) of less than 20; a melt index ratio (MIR, ASTM D1238I21/I2) of from 35 to 80; an averaged modulus (M) of from 20 000 to 60000 psi (137.9 to 413.7 MPa) and a relation between M and the dartimpact strength, DIS, (determined by ASTM D1709, 26 inch) in g/mil (DIS)complying with the formula:

DIS≧0.8[100+exp(11.71−0.000268M+2.183×10⁻⁹M²)]

where M is the averaged modulus, as further described in U.S. Pat. No.6,255,426, the contents of which are incorporated in their entirety,including columns 7, line 5 through column 10, line 63. The averagedmodulus (M) is the sum of the 1% secant Modulus (ASTM D882) in themachine direction and the transverse direction divided by two. In apreferred embodiment, the DIS is from 120 to 1000 g/mil, preferably 150to 800 g/mil. In a preferred embodiment, the M_(w)/M_(r), is from 2.5 to5.5.

Particularly useful linear ethylene containing polymers are thosedescribed in U.S. Pat. No. 6,255,426.

In-Reactor Polymer Blend

As used herein the term “branched block copolymer” is defined as thecross product obtained when a first polymer chain (also referred asmacromonomer) with reactive polymerizable chain ends is incorporatedinto a second polymer chain during the polymerization of the latter toform a structure comprising a backbone defined by one of the polymerchains with branches of the other polymer chains extending from thebackbone. Backbone and branches possess different and unique molecularstructures, such as chemical composition and crystallinity. For example,a polyethylene homopolymer with vinyl chain ends can be incorporatedinto an ethylene copolymer chain to form a branched cross-product withan ethylene copolymer backbone and homopolyethylene side branches. Sincethe molecular structure/composition in the backbone and branches aredifferent, the branched block composition typically has characteristicsfrom both the backbone and the branches. The branched block products arealso referred to as branched cross products or cross products. In oneembodiment, the branches of branched block copolymer produced herein arecomprised of homopolyethylene and the backbone is comprised of ethylenecopolymers with at least one monomer selected from ethylene or C₃ to C₁₂alpha olefin. In another embodiment, both the backbone and branches inthe branched block polymer are comprised of ethylene copolymers, whereinthe difference in density between the copolymers in backbone andbranches is at least 1%, preferably at least 2%, more preferably atleast 3%.

To effectively incorporate a reactive polymer chain into the growingchains of another polymer, it is preferable that the macromonomersderived from at least one catalyst have reactive polymerizable chainends. Alternately a first polymerization step produces macromonomershaving reactive termini, such as vinyl end groups, in a processinvolving multiple steps. By macromonomers having reactive termini ismeant a polymer having twelve or more carbon atoms (preferably 20 ormore, more preferably 30 or more, more preferably between 12 and 8000carbon atoms) and having a vinyl, vinylidene, vinylene or other terminalgroup that can be polymerized into a growing polymer chain. Vinylterminated chains are generally more reactive than vinylene orvinylidene terminated chains. Generally, it is desirable that themacromonomers derived from at least one catalyst have at least 50%, suchas at least 70% of vinyl terminal unsaturations based on the totalunsaturated olefin chain ends. Alternatively it is desirable that thefirst polymerization step produces a polymer having at least 50%, suchas at least 60%, for example at least 70%, even at least 80% of vinylterminal unsaturation based on the total unsaturated olefin chain ends.Unsaturated chain ends (and percents thereof) are determined usingproton NMR (collection at 120° C., 400 MHz) as described in U.S. Ser.No. 12/143,663, filed Jun. 20, 2008, particularly the proceduredescribed on page 33 line 25 to page 34, line 11.

The in-reactor blends described herein are blended with at least oneethylene containing polymer to prepare the compositions of thisinvention. The in-reactor polymer blend comprises: (a) a first ethylenecontaining polymer having a density of greater than 0.90 g/cm³ and anM_(w) of more than 20,000 g/mol; and (b) a second ethylene containingpolymer having a density of less than 0.90 g/cm³, wherein the polymerblend has a T_(m) of at least 90° C. (DSC second melt), a density ofless than 0.92 g/cm³, and the densities of the first and second polymerdiffer by at least 1% (preferably be at least 2%, preferably by at least3%, preferably by at least 5%). Alternately the densities differ by atleast 0.01 g/cm³, preferably by at least 0.02 g/cm³, preferably by atleast 0.03 g/cm³, preferably by at least 0.035 g/cm³.

The in-reactor polymer blend comprises: (a) a first ethylene polymercomprising 90 wt % to 100 wt % ethylene (preferably 95 wt % to 100 wt %)and from 0 wt % to less than 10 wt % comonomer (preferably 0 wt % to 5wt %), said first ethylene polymer component having density of greaterthan 0.920 g/cm³, an M_(w) of 20,000 g/mol or more and optionally aT_(m) of 110° C. or more; and (b) a second ethylene polymer comprisingfrom 70 wt % to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, saidsecond ethylene polymer having a density of 0.910 g/cm³ or less, whereinthe in-reactor polymer blend has one or more of the followingcharacteristics:

-   -   (a) at least 78 wt % ethylene;    -   (b) a T_(m) of at least 100° C. over a density ranging from 0.84        to 0.92 g/cm³;    -   (c) an elongation at break of 300% or more;    -   (d) a strain hardening ratio, M300/M100, of at least 1.2,        preferably of at least 1.3;    -   (e) a ratio of complex viscosity at 0.01 rad/s to the complex        viscosity at 100 rad/s of at least 30; and    -   (f) a shear thinning index of less than −0.2.

In one aspect, the in-reactor polymer blends have high meltingtemperature over a wide range of density from 0.84 to 0.92 g/cm³. Themelting temperature of traditional random copolymers ofethylene/alpha-olefins decreases with decreasing densities. In contrast,the in-reactor polymer blends exhibit melting points substantiallyindependent of the density, particularly when density is between about0.84 to about 0.92 g/cm³. For example, the melting points of suchpolymer blends are in the range of about 100° C. to about 130° C. whendensity ranges from 0.84 to about 0.92 g/cm³. In some embodiments, themelting points of polymer blends are in the range of about 100° C. toabout 125° C. when density ranges from 0.84 to about 0.92 g/cm³.

The in-reactor polymer blend described herein has a unique combinationof strong shear thinning and strong mechanical properties, such aselongation and tensile strength and comprises an ethylene-containingfirst polymer; an ethylene-containing second polymer different indensity from the first polymer by at least 0.03 g/cm³, typically atleast 0.035 g/cm³; and a branched block copolymer having a backbonecomprising the second polymer and branches comprising the first polymer.Preferably, the higher density material is employed as the first polymerand hence as the side branches of the branched block copolymer.

Branched block structures can be observed by Small Amplitude OscillatoryShear (SAOS) testing of the molten polymer performed on a dynamic(oscillatory) rheometer. From the data generated by such a test it ispossible to determine the phase or loss angle δ, which is the inversetangent of the ratio of G″ (the loss modulus) to G′ (the storagemodulus). For a typical linear polymer, the loss angle at lowfrequencies (or long times) approaches 90°, because the chains can relaxin the melt, adsorbing energy, and making the loss modulus much largerthan the storage modulus. As frequencies increase, more of the chainsrelax too slowly to absorb energy during the oscillations, and thestorage modulus grows relative to the loss modulus. Eventually, thestorage and loss moduli become equal and the loss angle reaches 45°. Incontrast, a branched chain polymer relaxes very slowly, because thebranches need to retract before the chain backbone can relax along itstube in the melt. This polymer never reaches a state where all itschains can relax during an oscillation, and the loss angle never reaches90° even at the lowest frequency, w, of the experiments. The loss angleis also relatively independent of the frequency of the oscillations inthe SAOS experiment; another indication that the chains cannot relax onthese timescales.

In a plot of the loss or phase angle δ versus the measurement frequency,ω, polymers that have long chain branches exhibit a plateau in thefunction of δ(ω), whereas linear polymers do not have such a plateau.According to Garcia-Franco et al. (Macromolecules 2001, 34, No. 10, pp.3115-3117), the plateau in the aforementioned plot will shift to lowerphase angles δ when the amount of long chain branching occurring in thepolymer sample increases. Dividing the phase angle at which the plateauoccurs by a phase angle of 90°, one obtains the critical relaxationexponent n which can then be used to calculate a gel stiffness using theequation:

η*(ω)=SΓ(1−n)ω^(n-1)

wherein η* represents the complex viscosity (Pa·s); ω represents thefrequency; S is the gel stiffness; Γ is the gamma function (see Beyer,W. H. Ed., CRC Handbook of Mathematical Sciences 5^(th) Ed., CRC Press,Boca Rotan, 1978); and n is the critical relaxation exponent. Polymersproduced herein preferably have a gel stiffness of more than 150 Pa·s,preferably at least 300 Pa·s and more preferably at least 500 Pa·s. Thegel stiffness is determined at the test temperature of 190° C. Apreferred critical relaxation exponent n for the in-reactor blends usedherein is less than 1 and more than 0, generally, n will be between 0.1and 0.92, preferably between 0.2 and 0.85.

The Small amplitude oscillatory shear (SAOS) data can be transformedinto discrete relaxation spectra using the procedure on pages 273-275 inR. B. Bird, R. C. Armstrong, and O. Hassager, Dynamics of PolymericLiquids, Volume 1, Fluid Mechanics, 2^(nd) Edition, John Wiley and Sons,(1987). The storage and loss moduli are simultaneously least squares fitwith the functions

G′(ω_(j))=Ση_(k)λ_(k)ω_(j) ²/(1+(η_(k)ω_(k))²)

G″(ω_(j))=Ση_(k)λ_(k)ω_(j)/(1+(η_(k)ω_(k))²)

at the relaxation times λ_(k)=0.01, 0.1, 1, 10, and 100 seconds.Therefore, the sums are from k=1 to k=5. The sum of the η_(k)'s is equalto the zero shear viscosity, η₀. An indication of high levels ofbranched block products is a high value of η₅, corresponding to therelaxation time of 100 s, relative to the zero shear viscosity. Theviscosity fraction of the 100 s relaxation time is η₅ divided by thezero shear viscosity, η₀. For the in-reactor polymer blends useful inthis invention the viscosity fraction of the 100 second relaxation timeis preferably at least 0.1, more preferably 0.4, and most preferably0.8. In contrast, viscosity fractions of 100 second chains ofconventional isotactic polypropylene are of the order of 0.10 or lessand of conventional propylene/ethylene copolymers are of the order of0.10 or less. Chains with long relaxation times cannot relax during thecycle time of the SAOS experiment and lead to high zero shearviscosities.

The in-reactor polymer blends used in this invention have good shearthinning Shear thinning is characterized by the decrease of complexviscosity with increasing shear rate. One way to quantify the shearthinning is to use a ratio of complex viscosity at a frequency of 0.01rad/s to the complex viscosity at a frequency of 100 rad/s. Preferably,the complex viscosity ratio of the invented polymer blend is 30 or more,more preferably 50 or more, even more preferably 100 or more when thecomplex viscosity is measured at 190° C.

Shear thinning can be also characterized using a shear thinning index.The term “shear thinning index” is determined using plots of thelogarithm (base ten) of the dynamic viscosity versus logarithm (baseten) of the frequency. The slope is the difference in the log (dynamicviscosity) at a frequency of 100 rad/s and the log(dynamic viscosity) ata frequency of 0.01 rad/s divided by 4. These plots are the typicaloutput of the SAOS experiments. For ethylene/propylene copolymers, aconventional SAOS test temperature is 190° C. Polymer viscosity isconveniently measured in poise (dyne-second/square centimeter) or Pa·s(1 Pa·s=10 poises) at shear rates within a range of from 0 to 100rad/sec and at 190° C. under a nitrogen atmosphere using a dynamicmechanical spectrometer, such as the Advanced Rheometrics ExpansionSystem (ARES). Generally a low value of shear thinning index indicates apolymer is highly shear-thinning and that it is readily processable inhigh shear processes, for example by injection molding. The morenegative this slope, the faster the dynamic viscosity decreases as thefrequency increases. Preferably, the in-reactor polymer blend has ashear thinning index of less than −0.2. These types of polymer blendsare easily processed in high shear rate fabrication methods, such asinjection molding.

Useful in-reactor polymer blends described herein have tensile strengthgreater than 15 MPa (as measured by ASTM D638 at 23° C.), preferablygreater than 20 MPa, preferably greater than 30 MPa.

Useful in-reactor polymer blends described herein have elongation atbreak greater than 300% (as measured by ASTM D638 at 23° C.), preferablygreater than 400%, preferably greater than 500%, preferably greater than600%, preferably greater than 700%, preferably greater than 800%,preferably greater than 900%.

Useful in-reactor polymer blends described herein have tensile strengthat 100% elongation greater than 8 MPa (as measured by ASTM D638 at 23°C.), preferably greater than 10 MPa, preferably greater than 12 MPa.

In some embodiments, the in-reactor polymer blends have a tensilestrength above 8 MPa, preferably a tensile strength above 10 MPa, and/oran elongation at break of at least 600%, preferably at least 700%,preferably at least 800%, and preferably at least 900%.

Useful in-reactor polymer blends described herein also show strainhardening in tensile measurements. After the yield point, the blendundergoes a period of strain hardening, in which the stress increasesagain with increasing strain up to the ultimate strength in astress-strain curve as measured according to ASTM D638. Strain hardeningis measured by a ratio of a stress at 300% of strain (M300) to thestress at 100% of strain (M100). The ratio of M300/M100 greater than 1indicates strain hardening. The degree of strain hardening can also bemeasured using a ratio of M100 to a stress at 500% or 800% of strain.M500/M100 is defined as a ratio of the stress at 500% strain to thestress at 100% strain. Likewise, M800/M100 is defined as a ratio of thestress at 800% strain to the stress at 100% strain.

Preferred in-reactor polymer blends useful herein have a M300/M100strain hardening ratio greater than 1.2, preferably greater than 1.3,preferably greater than 1.4, preferably greater than 1.5, preferablygreater than 1.6; and/or a M500/M100 strain hardening ratio greater than1, preferably greater than 1.03, preferably greater than 1.05; and/or aM800/M100 strain hardening ratio greater than 1, preferably greater than1.1, preferably greater than 1.2. Alternatively, the in-reactor polymerblends described herein have a strain hardening ratio Mx/M100 greaterthan 1.2, where Mx is the tensile strength at break.

Useful in-reactor polymer blends described herein also have a toughness(as measured by ASTM D638) of 40 MJ/m³ or more, preferably 50 MJ/m³ ormore, preferably 60 MJ/m³ or more. Toughness is defined as the abilityof polymer to absorb applied energy up to break. The area under thestress-strain curve (ASTM D638 at 23° C.) is used as a measure of thetoughness at room temperature.

The branched block composition in the present in-reactor polymer blendcan comprise a wide variety of structural compositions enabling thetensile properties to be tuned over a wide range. While not wishing tobe bounded by any theory, it is believed that in addition to thebranched block structural composition, the crystalline polymers formhard inclusions (or crystallites) within a soft matrix so that physicalcrosslinks are formed in the polymer blend. The presence of physicalcrosslink promotes tensile properties. To be effective, the highcrystalline hard inclusions are multi-blocks with low crystalline oramorphous chain segments. The low crystalline or amorphous chainsegments should be long enough to span the distance between two hardinclusions or entangled with other chain segments from other hardinclusions.

In one embodiment, the components on the side branches and backbone aswell as individual components in the in-reactor blend are immiscible sothat the blend has a heterogeneous morphology. One advantageousheterogeneous blend comprises the lower crystallinity polymer componentin dispersed phase and the higher crystallinity polymer in thecontinuous phase. For some applications, the blends have a wide range inmorphology as the components of greater and lesser crystallinity canalso be co-continuous. Alternatively, the in-reactor blend can have aheterogeneous morphology with the higher crystalline component in adispersed phase and the lesser crystalline component in a continuousphase. In any event, the sizes of the individual domains of thedispersed phase are very small with the smallest length dimension forthe dispersed phase typically being less than 5 μm, such as less than 2μm, even less than 1 μm without any compatibilizer added. While notwishing to be restrained by any theory, we believe that the reason forthe small domain size is the presence of branched block structures whichhas the attributes of both the first polymer and the second polymercomponent. In particular, we believe that such a molecule containingsegments of each of the polymeric components acts like compatibilizer inthe in-reactor blend. The presence of branched block composition enablesimmiscible components in the blend to be compatible to the extent thatno compatibilizer is needed in order to attain and retain this finemorphology. Presence of fine particles of the dispersed phase generallyallows dispersion of higher amounts of the dispersed phase in a polymermatrix, stabilizes the obtained morphology by preventing coalescence ofthe dispersed particles, and enhances mechanical properties of theblend. This also allows the production of softer in-reactor polymerblends.

For purposes of this invention and the claims thereto, a “heterogeneousblend” is a composition having two or more morphological phases in thesame state. For example a blend of two polymers where one polymer formsdiscrete packets (or finely divided phase domains) dispersed in a matrixof another polymer is said to be heterogeneous in the solid state. Alsoa heterogeneous blend is defined to include co-continuous blends wherethe blend components are separately visible, but it is unclear which isthe continuous phase and which is the discontinuous phase. Suchmorphology is determined using atomic force microscopy (AFM). Bycontinuous phase is meant the matrix phase in a heterogeneous blend. Bydiscontinuous phase is meant the dispersed phase in a heterogeneousblend. The finely divided phase domains of the discontinuous phase arealso referred as particles. In contrast, a “homogeneous blend” is acomposition having substantially one morphological phase in the samestate. For example, a blend of two polymers where one polymer ismiscible with another polymer is said to be homogeneous in the solidstate. Such morphology is determined using scanning electron microscopy.By miscible is meant that that the blend of two or more polymersexhibits single-phase behavior for the glass transition temperature,e.g., the T_(g) would exist as a single, sharp transition temperature ona dynamic mechanical thermal analyzer (DMTA) trace of tan δ (i.e., theratio of the loss modulus to the storage modulus) versus temperature. Bycontrast, two (or more) separate transition temperatures would beobserved for an immiscible blend, typically corresponding to thetemperatures for each of the individual components of the blend. Thus, apolymer blend is miscible when there is one T_(g) indicated on the DMTAtrace. A miscible blend is homogeneous, while an immiscible blend isheterogeneous.

Alternatively, the components on the side branches and backbone as wellas individual components in the in-reactor blend are miscible. Thein-reactor produced polymer blend then has homogeneous morphology. Whenall the individual components are capable of crystallizing to a limitedextent, they are at least partially co-crystallized.

In one practical embodiment, the present in-reactor polymer blendincludes a branched block copolymer in which the branches are comprisedof an ethylene homopolymer and the backbone is comprised of an ethylenecopolymer with at least one monomer selected from C₃ to C₁₂ alphaolefin. In another embodiment, both the backbone and branches in thebranched block polymer are comprised of ethylene copolymers, wherein thedifference in density between the copolymers in backbone and branches isat least 1%, such as at least 2%, for example at least of 3%.

The in-reactor polymer blends have a density in a range of from 0.840g/cm³ to 0.940 g/cm³ in one embodiment, from 0.850 g/cm³ to 0.93 g/cm³in a more particular embodiment, from 0.850 g/cm³ to 0.920 g/cm³ in yeta more particular embodiment, from 0.860 g/cm³ to 0.930 g/cm³ in yet amore particular embodiment, from 0.870 g/cm³ to 0.92 g/cm³ in yet a moreparticular embodiment, less than 0.925 g/cm³ in yet a more particularembodiment, less than 0.920 g/cm³ in yet a more particular embodiment,and less than 0.900 g/cm³ in yet a more particular embodiment.

The in-reactor polymer blends preferably have a bulk density of from0.400 to 0.900 g/cm³ in one embodiment, and from 0.420 to 0.800 g/cm³ inanother embodiment, and from 0.430 to 0.500 g/cm³ in yet anotherembodiment, and from 0.440 to 0.60 g/cm³ in yet another embodiment,wherein a desirable range may comprise any upper bulk density limit withany lower bulk density limit described herein.

Preferably, the in-reactor polymers blend has an MI (I2, as measured byASTM D1238, 190° C./2.16 kg) in the range of from 0.01 dg/min to 100dg/min in one embodiment, from 0.01 dg/min to 50 dg/min in a moreparticular embodiment, from 0.02 dg/min to 20 dg/min in yet a moreparticular embodiment, and from 0.03 dg/min to 2 dg/min in yet a moreparticular embodiment, and from 0.002 dg/min to 1 dg/min in yet a moreparticular embodiment.

Preferably, the polymers blend has an HLMI (I21, as measured by ASTMD1238, 190° C./21.6 kg) value that ranges from 0.01 to 800 dg/min in oneembodiment, and from 0.1 to 500 dg/min in another embodiment, and from0.5 to 300 dg/min in yet a more particular embodiment, and from 1 to 100dg/min in yet a more particular embodiment wherein a desirable range isany combination of any upper I21 limit with any lower I21 limit.

Preferably, the in-reactor polymer blends have a melt index ratio (MIRor I21/I2) of from 10 to 500 in one embodiment, from 15 to 300 in a moreparticular embodiment, and from 20 to 200 in yet a more particularembodiment. Alternately, the polymer blends have a melt index ratio ofgreater than 15 in one embodiment, greater than 20 in a more particularembodiment, greater than 30 in yet a more particular embodiment, greaterthan 40 in yet a more particular embodiment, and greater than 50 in yeta more particular embodiment.

First Ethylene Polymer (High Density Ethylene Polymer) in the In-ReactorPolymer Blend

In a preferred embodiment, the first ethylene polymer of the in-reactorblend is an ethylene polymer comprising 90 wt % to 100 wt % ethylene(preferably from 95 wt % to 100 wt % ethylene, preferably from 98 wt %to 100 wt % ethylene, preferably 100 wt % ethylene) and from 0 wt % toless than 10 wt % comonomer (preferably 0 wt % to 5 wt %, preferably 0wt % to 2 wt %, preferably 0 wt %), said first ethylene polymer havingdensity of greater than 0.920 g/cm³ (preferably greater than 0.930g/cm³, preferably between 0.920 g/cm³ and 0.96 g/cm³) and optionally aT_(m) of 100° C. or more (preferably from 90° C. to 130° C., preferablyfrom 100° C. to 130° C.).

In a preferred embodiment, the first ethylene polymer is an ethylenehomopolymer, such as high density polyethylene.

In another embodiment the first ethylene polymer has:

1) a molecular weight distribution (M_(w)/M_(n)) of up to 40 (preferablyranging from 1.5 to 20, and from 1.8 to 10 in another embodiment, andfrom 1.9 to 5 in yet another embodiment, and from 2.0 to 4 in yetanother embodiment); and/or

2) a weight average molecular weight (M_(w)) of 20,000 g/mol or more,preferably 30,000 g/mole or more, preferably 50,000 g/mol or more,preferably 100,000 g/mol or more, preferably 200,000 g/mol or more,preferably 300,000 g/mol or more; and/or

3) a melt index (MI) of 0.1 to 800 dg/min (alternately 1 to 100 dg/min,as measured according to ASTM D1238 (190° C., 2.16 kg)); and/or

4) a density of 0.920 g/cm³ or more, preferably 0.925 g/cm³ or more,preferably of 0.930 g/cm³ or more, preferably of 0.935 g/cm³ or more.

The first polymers are macromonomers with reactive chain ends.Preferably, the polymers have at least 50%, such as at least 60%, forexample at least 70%, even at least 80% of vinyl terminal unsaturationbased on the total unsaturated olefin chain ends.

Second Ethylene Polymer (Ethylene Plastomer) in the In-Reactor PolymerBlend

In a particularly desirable embodiment, the second ethylene polymer ofthe in-reactor blend is an ethylene copolymer having a density of 0.910g/cm³ or less, as determined by ASTM D1505 (preferably from above 0.84g/cm³ to less than 0.910 g/cm³), and a melt index (MI) of 200 dg/min orless, as determined by ASTM D1238 (190° C., 2.16 kg). In one embodiment,the second ethylene polymer is a copolymer of ethylene and at least oneC₃ to C₁₂ α-olefin, preferably at least one C₄ to C₈ α-olefin(preferably at least one of propylene, butene, hexene, octene, anddecene). The amount of C₃ to C₁₂ α-olefin present in the ethylenecopolymer ranges from 2 wt % to 45 wt % in one embodiment, and from 10wt % to 30 wt % in another embodiment, and from 15 wt % to 25 wt % inyet another embodiment, and from 20 wt % to 30 wt % in yet anotherembodiment.

Preferred second ethylene polymers (also referred to as “plastomers”)useful in the invention typically have a melt index of 200 dg/min orless, alternately 100 dg/min or less in one embodiment, and from 0.2 to50 dg/min in another embodiment, and from 0.5 to 30 dg/min in yetanother embodiment. The weight average molecular weight of preferredplastomers ranges from 10,000 to 800,000 g/mole in one embodiment, andfrom 20,000 to 700,000 g/mole in another embodiment. The 1% secantflexural modulus (ASTM D790) of preferred plastomers ranges from 5 MPato 100 MPa in one embodiment, and from 10 MPa to 50 MPa in anotherembodiment. Further, preferred plastomers that are useful incompositions of the present invention have a melting temperature (T_(m)first melt peak) of from 0° C. to 100° C. in one embodiment, and from10° C. to 80° C. in another embodiment. The degree of crystallinity ofpreferred plastomers is between 3% and 30%.

Particularly preferred polymers useful in the present invention aresynthesized using a single-site catalyst, such as a metallocenecatalyst, and comprise copolymers of ethylene and higher α-olefins suchas propylene, 1-butene, 1-hexene and 1-octene, and which contain enoughof one or more of these comonomer units to yield a density between 0.86g/cm³ and 0.91 g/cm³ in one embodiment. The molecular weightdistribution (M_(w)/M_(n)) of desirable plastomers ranges from 1.5 to 5in one embodiment and from 2.0 to 4 in another embodiment.

Preferably, the difference in the peak melting temperatures between thefirst high crystalline polymer and the second low crystalline polymer is20° C. or more, for example 30° C. or more, for example 40° C. or more.

The ratio of the first polymer component to the second polymer componentin the reactor blend depends on the requirements of the end-useapplications. The thermal properties of the final in-reactor polymerblend depend on the properties of each component and the ratio of eachcomponent in the blend. Generally, the in-reactor blend has acrystallinity of 80% or less, typically 70% or less, as calculated usingheat of fusion obtained from DSC analysis. A sum of the heat of fusionfrom all melting peaks is used when multiple melting peaks are present.The heat of fusion for 100% crystallinity is selected from thehomopolymer of the primary composition in the in-reactor polymer blend.For example, when the polymer blend is made of an ethylene homopolymerand ethylene/hexene copolymer, ethylene is the primary composition, andthe heat of fusion of 100% crystalline polyethylene is used (e.g., 290J/g). In one embodiment, the in-reactor produced polymer blend has aheat of fusion between about 10 and about 270 J/g, for example betweenabout 30 and about 200 J/g, such as between about 40 and about 200 J/g.

Conveniently, the in-reactor polymer blend typically has a meltingtemperature of 100° C. or more, and generally 110° C. or more, such as115° C. or more, for example 120° C. or more. The term “melting point,”as used herein, for the in-reactor polymer blend, is the highesttemperature peak among principal and secondary melting peaks asdetermined by DSC. In one embodiment of the present invention, thepolymer has a single melting peak. Typically, a sample of in-reactorpolymer blend will show secondary melting peaks adjacent to theprincipal peak, which peaks are considered together as a single meltingpeak. The highest of these peaks is considered the melting point. Thein-reactor polymer blend preferably has a melting point by DSC rangingfrom an upper limit of 130° C., 120° C., 110° C., 100° C., or 90° C., toa lower limit of 20° C., 30° C., 40° C., or 50° C.

Typically, the in-reactor blend has crystallization temperature of 130°C. or less. The term “peak crystallization temperature” or“crystallization temperature” as used herein, for the in-reactor polymerblend, is the highest temperature peak among principal and secondarycrystallization peaks as determined by DSC. In one embodiment of thepresent invention, the polymer has a single crystallization peak. Whenthe crystallinity of the first and the second polymer components in thein-reactor blend is close, the polymer blend will show secondarycrystallization peaks adjacent to the principal peak, which peaks areconsidered together as a single crystallization peak. The highest ofthese peaks is considered the peak crystallization temperature. When thecrystallinity of the first and the second polymer components in thein-reactor blend is far apart, the polymer blend will show twoindividual peaks for each component. The in-reactor polymer blendpreferably has a crystallization temperature by DSC ranging from anupper limit of 120° C., 100° C., 90° C., 70° C., or 40° C., to a lowerlimit of 0° C., 10° C., 30° C., 40° C., or 70° C.

The melting temperatures of the in-reactor polymer blend produceddirectly reflect the degree of crystallinity of the crystalline polymercomponent in the blend. The polymer blend can have a high meltingtemperature in a wide range of densities. In one embodiment, the polymerproduced has a melting temperature of 100° C. or higher and a density of0.920 g/cm³ or less, preferably 110° C. or higher and a density of 0.900g/cm³ or less, more preferably 115° C. or higher and a density of 0.880g/cm³ or less. Lower value of density means softer materials.Alternatively, the in-reactor polymer blends have shore hardness from 30A to 40 D and a melting temperature of 110° C. or higher.

Conveniently, the in-reactor blend has a weight average molecular weightof between 20,000 and 2,000,000 g/mol, such as between 30,000 and1,500,000 g/mol with a polydispersity index (PDI=M_(w)/M_(n)) in therange of 1.5 to 40. The polydispersity index is partially dependent onthe catalysts and process condition employed in the polymerizationprocess. For example, polymerization involving multiple catalysts mayproduce a copolymer with broader or multimodal molecular weightdistribution. Multiple reactors with different polymerization conditionsmay produce polymer blend with multimodal molecular weightdistributions. In one embodiment the polymer blend produced may have aunimodal, bimodal, or multimodal molecular weight distribution. Bybimodal or multimodal is meant that the SEC trace has more than one peakor inflection points. An inflection point is that point where the secondderivative of the curve changes in sign (e.g., from negative to positiveor vice versa).

The molecular weight of each component in the in-reactor polymer blendcan be optimized for a specific application. Generally, the molecularweight of the crystalline component should be greater than theentanglement molecular length, while the molecular weight of the lesscrystalline or amorphous component should be long enough so thecrystalline component can bind the polymer segments together into aphysical network in the solid state. When the molecular weight of thefirst polymer is low, the second polymer should have higher molecularweight to attain good mechanical strength.

Preferred in-reactor polymer blends have a lower molecular weight/higherdensity polyethylene component and a higher molecular weight/lowerdensity component.

The amount of the first polymer relative to the second polymer componentmay vary widely depending on the nature of the component polymers andintended end use of the polymer blend. In particular, however, oneadvantage of the present process is the ability to be able to produce apolymer blend in which the lower crystalline propylene copolymercomprises more than 20%, such as more than 50%, for example more than70% of the total in-reactor polymer blend.

A polymer blend can be separated into fractions by solvent extraction(also referred as fractionation). A typical solvent is a saturatedhydrocarbon, such as hexane, cyclohexane, heptane, or xylene. Theextraction temperature can range from room temperature to the boilingpoint of the solvent. Polymers are easier to dissolve if they arepressed into a thin film and then cut into small pieces. They can alsobe milled into granules or powder prior to dissolving. For polymerblends containing homopolyethylene, the polyethylene component can beseparated using cyclohexane refluxing for 24 hours. The insolublefraction comprises polyethylene and part of the branched block products.For in-reactor blends containing low crystallinity plastomeric orelastomeric component, the low crystallinity component can be isolatedby contacting the blend with cyclohexane at 25° C. for 48 hours. Thesoluble fraction comprises the low crystallinity plastomeric orelastomeric component. Alternatively, a differential solventfractionation of the in-reactor polymer blend with several solvents ofprogressively increasing solubility and boiling point can provideseveral fractions. Nominally, about 10 grams of the in-reactor blend iscontacted with about 500 ml of cyclohexane in a thick-walled glassbottle with a screw cap closure. The sealed bottle is maintained at 25°C. for 48 hours. At the end of this period, the solution isdecanted/filtered and evaporated to yield a residue of the polymersoluble to cyclohexane at 25° C. To the insoluble residue is addedsufficient cyclohexane to bring the volume to about 500 ml and thebottle is then maintained at 30° C. for 48 hours. The soluble polymer isdecanted/filtered and evaporated to yield a residue of the polymersoluble to cyclohexane at 30° C. In this manner, fractions of thein-reactor blends soluble at a temperature from 40° C. to 60° C. areobtained at temperature increases of approximately 5° C. between stages.Increases in temperature to over 100° C. can be accommodated if xylene,instead of cyclohexane, is used as the solvent. The temperature andtemperature interval can be varied according to the distribution of thein-reactor blends.

Conveniently, the in-reactor blend has a cyclohexane refluxing insolublefraction of 70 wt % or less, preferably 60 wt % or less. Alternatively,the in-reactor blend has a cyclohexane room temperature soluble fractionof 20 wt % or more, preferably 30 wt % or more, more preferably 40 wt %or more.

In one embodiment, the present in-reactor polymer blend has a fractionwhich elutes between 50° C. to 100° C. and a soluble fraction whichelutes below 5° C. when fractionated using Temperature Rising ElutionFractionation (TREF) using the procedure described in the ExperimentalSection. The fraction corresponding to the highest temperature peak isreferred to as the high-crystalline fraction. The soluble fraction istherefore referred to as the amorphous elastomeric component. Dependingon the crystallinity of the first and second polymers as well as thebranched block composition, the peak temperature may be shifted or theremay be additional peaks. Alternatively, a fraction elutes at temperaturebetween 0° C. and 70° C. when a semi-crystalline ethylene copolymer suchas plastomer is present in the blend.

In conducting the ¹³C NMR investigations, samples are prepared by addingabout 0.3 g sample to approximately 3 g of tetrachloroethane-d2 in a 10mm NMR tube. The samples are dissolved and homogenized by heating thetube and its contents to 150° C. The data are collected using a Varianspectrometer, with corresponding ¹H frequencies of either 400 or 700MHz. The data are acquired using nominally 4000 transients per data filewith a about a 10 second pulse repetition delay. To achieve maximumsignal-to-noise for quantitative analysis, multiple data files may beadded together. The spectral width was adjusted to include all the NMRresonances of interest and FIDs were collected containing a minimum of32K data points. The samples are analyzed at 120° C. in a 10 mm broadband probe. Assignments of peaks for ethylene/propylene,ethylene/butene, ethylene/hexene, and ethylene/octene copolymers havebeen reviewed by James C. Randall in Polymer Reviews, 29 (2), pp.201-317, (1989). Assignments for ethylene-hexene copolymers were takenfrom M. R. Seger and G. E. Maciel, Anal. Chem. 2004, 76, pp. 5734-5747.

Although the branch points for long chain branched polymers can be seenin ¹³C NMR for some compositions, they are difficult to measure in thespectra of ethylene/hexene copolymers (or ethylene copolymers withcomonomers larger than C₆). The short chain branch points associatedwith the hexene (or larger) comonomers occur at similar chemical shiftsto the chemical shifts of long chain branch points, making themimpossible to integrate.

For in-reactor polymer blends with low content of branched blockcomposition, the blends should be first fractionated into components.Signals for the branched block components are found in the samefractions as the high crystallinity polyethylene components sincemajority of the cross products between polymers with differentcrystallinities will remain in the higher crystallinity fraction of thein-reactor blend.

In a preferred embodiment, the in-reactor blends of this inventioncomprise: (i) a first ethylene polymer comprising 90 wt % to 100 wt %(preferably 92 wt % to 99 wt %, preferably 95 wt % to 97 wt %) ethyleneand from 0 wt % to less than 10 wt % (preferably 1 wt % to 8 wt %,preferably 3 wt % to 5 wt %) comonomer (preferably propylene, butene,hexene, or octene), said first ethylene component having a melting pointof 90° C. or more (preferably 100° C. or more, preferably 110° C. ormore); and (ii) a second ethylene polymer comprising from 30 wt % to 90wt % (preferably 35 wt % to 85 wt %, preferably 40 wt % to 80 wt %)ethylene and 70 wt % to 10 wt % (preferably 65 wt % to 15 wt %,preferably 60 wt % to 20 wt %) comonomer (preferably propylene, butene,hexene, or octene), said second ethylene polymer having an M_(w) of20,000 g/mol or more, preferably 30,000 g/mol or more, preferably 50,000g/mol or more and a melting point of 100° C. or less, preferably from10° C. to 100° C., preferably from 20° C. to 85° C.

In another embodiment, the in-reactor polymer blends produced hereinhave a heat distortion temperature of 60° C. or more measured at 1.8 MPaaccording to ASTM D648.

Another unique feature of the in-reactor blend material is a broadapplication temperature range. In one embodiment, the applicationtemperature is between −40° C. to 160° C., preferably from −30° C. to130° C., more preferably from −20° C. to 120° C. The in-reactor blendcomprises the high density ethylene copolymer component which has amelting point of greater than 90° C. and low density ethylene copolymercomponent which has a glass transition temperature as low as −70° C. Thebranched block cross products possess the characteristics derived fromboth the high and low density ethylene copolymer such as low glasstransition temperature from low density component (−70° C. or less) andhigh melting temperature from long sequences of methylenes (polyethylenetype crystallinity) (90° C. or more). Consequently, it has a muchbroader use temperature over a wide range of density.

Process for Producing the In-Reactor Polymer Blend

The in-reactor polymer blends described herein can be produced using anyappropriate polymerization techniques known in the art. Polymerizationmethods include high pressure, slurry, gas, bulk, suspension,supercritical, or solution phase, or a combination thereof, using asingle-site metallocene catalyst system. The catalysts can be in theform of a homogeneous solution, supported, or a combination thereof.Polymerization may be carried out by a continuous, a semi-continuous orbatch process and may include use of chain transfer agents, scavengers,or other such additives as deemed applicable.

The in-reactor polymer blends can be produced in a single reaction zonewith at least two catalysts. At least one of the catalysts is capable ofproducing high crystalline polyethylene having a density of 0.92 g/cm³or more, and another catalyst is capable of producing low crystallinitypolymer having a density of 0.91 g/cm³ or less in the samepolymerization medium. The two catalysts can be fed into the reactor ashomogeneous catalyst solution through separated feed lines or inpremixed form. The two catalysts can be also supported on a separatedsupport materials or supported on the same support material. Selectionsof the catalyst pair depend on, among many other factors, the catalystactivity as well as their capability of comonomer incorporation.Preferably, at least one catalyst is capable of producing polymer withreactive chain ends and at least one catalyst is capable of incorporatepolymer with reactive chain end to form branched polymers. The catalystratio needs to be tuned to meet the product requirement for specificend-use applications. Preferred metallocenes are those selected fromformulas (I), (II), (III), and (IVa) (described below) which when usedwith other catalysts, are capable of producing an polyethylene having adensity of 0.92 g/cm³ at commercially attractive temperatures of fromabout 50° C. to about 150° C. Preferably two or more metallocenes areselected which produce polymers having different molecular weights. Thisresults in a broader molecular weight distribution.

The in-reactor polymer blend described herein can be produced byinitially contacting ethylene in a first reaction zone with apolymerization catalyst capable of producing a polyethylene having adensity of 0.920 g/cm³ or more. At least part of the contents of thefirst reaction zone are then transferred into a separate second reactionzone together with one or more monomer selected from ethylene or C₃ toC₁₂ alpha-olefins and mixtures thereof so as to produce elastomer orplastomer in the presence of polyethylene produced in the first reactionzone.

In one embodiment, the second reaction zone employs the same catalystsystem transferred from the first reaction zone, with no additionalcatalyst being supplied to the second reaction zone. Alternatively, anadditional amount of the same catalyst system as used in the firstreaction zone is fed into the second reaction. Generally between about10% and about 90%, such as between about 20% and about 80%, for examplebetween about 30% and about 70% of the total catalyst is supplied to thefirst reaction zone, with the remainder being supplied to the secondreaction zone. The molar ratio of the catalyst supplied to the firstreaction zone to the catalyst supplied to the second reaction zonedepends on the end-use requirements of the in-reactor polymer blend.

In another embodiment, the catalyst system includes a firstpolymerization catalyst fed to the first reaction zone, and a secondpolymerization catalyst different from the first catalyst and capable ofproducing an elastomer or a plastomer having a density of 0.92 g/cm³ orless fed to the second reaction zone. The molar ratio of the firstpolymerization catalyst to the second polymerization catalyst isgenerally from 5:95 to 95:5 depending on the application and otherprocess variables. The resultant intimate mixing among the differentcomponents of the in-reactor produced polymer blend provides excellentinterface bonding and enhanced mechanical properties.

In one embodiment, all the ethylene is fed into the first reaction zone.Alternatively, ethylene feed is split between the first and secondreaction zones. Generally between about 30% and about 90%, such asbetween about 40% and about 80%, for example between about 50% and about70%, such as between about 45% and about 55% of the total ethylene issupplied to the first reaction zone, with the remainder being suppliedto the second reaction zone.

In another embodiment, the in-reactor polymer blend can be produced bycontacting ethylene and one or more monomers selected from C₃ to C₁₂alpha-olefins in a first reaction zone with a first polymerizationcatalyst capable of producing a polyethylene having a density of 0.92g/cm³ or more, and then supplying at least part of the contents of thefirst reaction zone together with optionally additional ethylene or oneor more of C₃ to C₁₂ alpha-olefins into a separate second reaction zonewherein an elastomer or a plastomer is produced in the presence ofethylene copolymer produced in the first reaction zone. The density ofthe ethylene copolymer produced in both the first and the secondreaction zones is mainly controlled through monomer incorporation. Thedifference in density between the two copolymers is preferably more than2%, even more preferably more than 3%. The second reaction zone canemploy the same catalyst system carried over from the first reactionzone. Alternatively, additional catalyst can be fed into the secondreaction zone. In another embodiment, a different catalyst can be usedin the second polymerization zone. All of ethylene can be fed into thefirst reaction zone. Alternatively, additional ethylene can be suppliedinto the second reaction zone.

The in-reactor polymer blends can be also produced by contactingethylene and one or more monomers selected from C₃ to C₁₂ alpha-olefinsin a first reaction zone with a first polymerization catalyst capable ofproducing a polyethylene having a density of 0.91 g/cm³ or less, andthen supplying at least part of the contents of the first reaction zonetogether with optionally additional ethylene or one or more of C₃ to C₁₂alpha-olefins into a separate second reaction zone wherein a higherdensity ethylene copolymer is produced in the presence of ethylenecopolymer produced in the first reaction zone. The density of theethylene copolymer produced in both the first and the second reactionzones is mainly controlled through monomer incorporation and catalyststructures. The same catalyst can be employed in both the first and thesecond reaction zone. Alternatively, the second catalyst is differentfrom the first catalyst.

In one embodiment, the catalyst employed to produce the second polymercomponent is the same as, or is compatible with, the catalyst used toproduce a thermoplastic first polymer component. In such a case, thefirst and second polymerization zones can be in a multiple-zone reactor,or separate, series-connected reactors, with the entire effluent fromthe first polymerization zone, including any active catalyst, beingtransferred to the second polymerization zone. Additional catalyst canthen be added, as necessary to the second polymerization zone. In aparticularly preferred embodiment, the present process is conducted intwo or more series-connected, continuous flow, stirred tank or tubularreactors using metallocene catalysts.

As described above, the contents of the first reactor zone aretransferred to the second reactor zone, and become a part of thereaction medium in the second reactor zone. The catalyst system employedin the first reactor zone is still active to continue the polymerizationreaction in the second reactor zone. Alternatively, a part or all of thesolvent and unreacted monomers are removed from the polymerizationeffluent in the first reactor zone, and the polymer, and remainingsolvent and monomers are transferred into the second reactor zone. Thiscan be implemented in a system with two reactors in series and a primaryseparator in between the two reactors. This process scheme also allowsindependent control of polymerization temperature in the first andsecond polymerization zones.

It is to be appreciated that, although the foregoing discussion refersonly to first and second polymerization zones, further reaction zonescould be employed, with the feed to the second reaction zone being splitbetween the additional reaction zones. However, from an economicviewpoint, such additional reaction zones are not currently preferred.

In-reactor polymer blends that can be made using the described processescan have a variety of compositions, characteristics and properties. Atleast one of the advantages is that the process utilized can be tailoredto form a polymer composition with a desired set of properties. Polymerswith bimodal distributions of molecular weight and composition can beproduced by the present polymerization process by, for example,controlling the polymerization conditions in the first and the secondpolymerization zones and/or by selecting the catalysts for the first andthe second polymerizations, such as by using multiple catalysts in eachpolymerization zone. Bimodal distributions of molecular weight andcomposition of the second polymer can also be obtained when differentcatalysts are used in the first and second polymerization zones and thecatalyst employed in the first polymerization zone is transferred intothe second polymerization zone for production of the branched blockpolymers.

In certain embodiments, a lower molecular weight and higher densitypolyethylene component is produced from the first catalyst which iscapable of producing polymer with a density of 0.92 g/cm³ or higher. Ahigher molecular weight and lower density polymer is produced from thesecond catalyst.

The amount of second polymer relative to the first polymer may varywidely depending on the nature of the polymers and the intended use ofthe final polymer blend. In particular, however, one advantage of thepresent process is the ability to be able to produce a polymer blend inwhich the second polymer comprises more than 50 wt %, such as more than60 wt %, for example more than 70 wt % of the total polymer blend. Forthermoplastic elastomer (TPE) applications, the weight ratio of thesecond polymer to the first polymer is generally from about 90:10 toabout 50:50, such as from about 80:20 to about 60:40, for example fromabout 75:25 to about 65:35. For TPO or impact copolymer applications,the weight ratio of the second polymer to the first polymer is generallyfrom about 49:51 to about 10:90, such as from 35:65 to about 15:85.

In an alternative embodiment, the first step of polymerization isreplaced by the use of a pre-made polymer, at least part of which hasreactive polymerizable chain ends. The pre-made polymer can be producedin a separate system or can be a commercially available product. Thecrystalline thermoplastic polymer can be dissolved in a solvent and thenadded into a reaction medium for the second polymerization step. Thecrystalline thermoplastic polymer can be also ground into fine powderand then added into the reaction medium for the second polymerizationstep.

Preferably, the polymerization is conducted in a continuous, stirredtank reactor. Tubular reactors equipped with the hardware to introducefeeds, catalysts and scavengers in staged manner can also be used.Generally, polymerization reactors are agitated (stirred) to reduce oravoid concentration gradients. Reaction environments include the casewhere the monomer(s) acts as diluent or solvent as well as the casewhere a liquid hydrocarbon is used as diluent or solvent. Preferredhydrocarbon liquids include both aliphatic and aromatic fluids, such asdesulphurized light virgin naphtha and alkanes, such as propane,isobutane, mixed butanes, hexane, pentane, isopentane, isohexane,cyclohexane, isooctane, and octane. In an alternate embodiment aperfluorocarbon or hydrofluorocarbon is used as the solvent or diluent.

More preferably, the polymerization is conducted by a continuoussolution process. Monomer concentration may be varied over a wide rangein a solution process. For most catalysts, high monomer concentrationimplies high productivity and high molecular weight of polymer formed.Polymer solubility in the reaction medium varies with the composition ofthe polymerization medium. The polymerization temperature and/orpressure can be adjusted to ensure a homogeneous phase polymerizationunder high monomer conditions. It is also desirable to have a goodbalance between polymer concentration, viscosity of the polymerizationmedium and energy consumption. Generally, the monomer concentration is 5wt % or more, such as 10 wt % or more, for example 15 wt % or more, even20 wt % or more, or 30 wt % or more, based on the total weight of thepolymerization medium including solvent, monomers and polymer produced.

The polymerization process conditions are generally selected to promotethe production of reactive macromonomers in the first polymerizationstep and the incorporation of side branches into the backbone in thesecond polymerization step. The reactive macromonomers also need to besoluble in the reaction medium so that they can re-incorporate intogrowing chains when a solution process is employed. Adequate mixing isalso important to ensure proper contact of the reactive macromonomerswith the growing backbone molecules. Higher monomer conversion or lowmonomer concentration in the second polymerization zone is alwayspreferred to boost the reactive macromonomer incorporation over monomerinsertion. In one embodiment, the monomer conversion in the secondpolymerization zone is 50% or more, such as 70% or more. In anotherembodiment, the monomer concentration in the second polymerization zoneis 5 mole/liter or less, such as 2 mole/liter or less, such as 1mole/liter or less, for example 0.5 mole/liter or less.

Another method of enhancing branch block compositions is to add a chaintransfer agent that transfers a vinyl group to the end of the polymerchain while deactivating the catalyst. Such chain transfer agentsinclude, but are not limited to, vinyl chloride, vinyl fluoride, vinylbromide. In the process, the catalyst is reactivated by the presence ofan aluminum alkyl activator, such as an alumoxane (typicallymethylalumoxane).

Suitable conditions for polymerization in each reaction zone include atemperature from about 50° C. to about 250° C., such as from about 50°C. to about 150° C., for example from about 70° C. to about 150° C. anda pressure of 0.1 MPa or more, such as 2 MPa or more. The upper pressurelimit is not critically constrained but is typically 200 MPa or less,such as 120 MPa or less, except when operating in supercritical phasethen the pressure and temperature are above the critical point of thereaction media in question (typically over 95° C. and 4.6 MPa forpropylene polymerizations). For more information on runningsupercritical polymerizations, see International Patent Publication No.WO 2004/026921. Temperature control in the reactor is generally obtainedby balancing the heat of polymerization with reactor cooling via reactorjackets or cooling coils, auto refrigeration, pre-chilled feeds,vaporization of liquid medium (diluent, monomers, or solvent), orcombinations of all three. Adiabatic reactors with pre-chilled feeds mayalso be used.

Where the polymerization is conducted in at least two reaction zones,the temperature employed in the first reaction zone is preferably lowerthan the temperature employed in the second reaction zone, typically byat least 10° C., such as at least 20° C. In one embodiment, thetemperature employed in the first reaction zone is between about 70° C.and about 180° C. and the temperature employed in the second reactionzone is between about 80° C. and about 200° C.

A polymer can be recovered from the effluent of either the firstpolymerization step or the second polymerization step by separating thepolymer from other constituents of the effluent using conventionalseparation means. For example, polymer can be recovered from eithereffluent by coagulation with a non-solvent such as isopropyl alcohol,acetone, or n-butyl alcohol, or the polymer can be recovered bystripping the solvent or other media with heat or steam. One or moreconventional additives such as antioxidants can be incorporated in thepolymer during the recovery procedure. Possible antioxidants includephenyl-beta-naphthylamine; di-tert-butylhydroquinone; triphenylphosphate; heptylated diphenylamine;2,2′-methylene-bis(4-methyl-6-tert-butyl)phenol; and2,2,4-trimethyl-6-phenyl-1,2-dihydroquinoline. Other methods of recoverysuch as by the use of lower critical solution temperature (LCST)followed by devolatilization are also envisioned. The catalyst may bedeactivated as part of the separation procedure to reduce or eliminatefurther uncontrolled polymerization downstream the polymer recoveryprocesses. Deactivation may be effected by the mixing with suitablepolar substances such as water, whose residual effect following recyclecan be counteracted by suitable sieves or scavenging systems.

Suitable catalysts are those capable of polymerizing a C₂ to C₂₀ olefinto produce an ethylene copolymer. These include both metallocene andZiegler-Natta catalysts. The catalysts employed in the first reactionzone should to able to produce polymers with reactive unsaturated chainends, preferably at least 50% of vinyl unsaturation based on the totalunsaturated olefin chain ends, while the catalyst used in the secondreaction zone should be capable of incorporating the polymerizablemacromonomer into a growing chain to form branched block polymers. Forpolymerization in single reaction zone using mixed catalysts, at leastone of the catalysts is able to produce polymers with reactiveunsaturated chain ends, preferably at least 50% of vinyl unsaturationbased on the total unsaturated olefin chain ends, while at least one ofthe catalysts is capable of incorporating the polymerizable macromonomerinto a growing chain to form branched block polymers. The catalysts canbe in the form of a homogeneous solution, supported, or a combinationthereof. In case of two catalysts are employed in the same reactionzone, preferably, at least one of the catalyst is able to incorporatemore comonomer (such as butene, hexene, or octene) than other catalystsso that the polymers produced will have different densities. A widevariety of transition metals compounds are known that, when activatedwith a suitable activator will have poor alpha-olefins incorporation andhence will produce higher density ethylene copolymers.

Metallocene catalyst compounds are generally described throughout in,for example, 1 & 2 METALLOCENE-BASED POLYOLEFINS (John Scheirs & W.Kaminsky eds., John Wiley & Sons, Ltd. 2000); G. G. Hlalky in 181COORDINATION CHEM. REV., pp. 243-296 (1999) and in particular, for usein the synthesis of polyethylene in 1 METALLOCENE-BASED POLYOLEFINS, pp.261-377 (2000). The metallocene catalyst compounds as described hereininclude “half sandwich” and “full sandwich” compounds having one or moreCp ligands (cyclopentadienyl and ligands isolobal to cyclopentadienyl)bound to at least one Group 3 to Group 12 metal atom, and one or moreleaving group(s) bound to the at least one metal atom. Hereinafter,these compounds will be referred to as “metallocenes” or “metallocenecatalyst components”.

The Cp ligands are typically π-bonded and/or fused ring(s) or ringsystems. The ring(s) or ring system(s) typically comprise atoms selectedfrom the group consisting of Groups 13 to 16 atoms, and moreparticularly, the atoms that make up the Cp ligands are selected fromthe group consisting of carbon, nitrogen, oxygen, silicon, sulfur,phosphorous, germanium, boron, aluminum, and combinations thereof,wherein carbon makes up at least 50% of the ring members. Even moreparticularly, the Cp ligand(s) may be selected from the group consistingof substituted and unsubstituted cyclopentadienyl ligands and ligandsisolobal to cyclopentadienyl, non-limiting examples of which includecyclopentadienyl, indenyl, fluorenyl, and other structures. Furthernon-limiting examples of such ligands include cyclopentadienyl,cyclopentaphenanthreneyl, indenyl, benzindenyl, fluorenyl,octahydrofluorenyl, cyclooctatetraenyl, cyclopentacyclododecene,phenanthrindenyl, 3,4-benzofluorenyl, 9-phenylfluorenyl,8-H-cyclopent[a]acenaphthylenyl, 7H-dibenzofluorenyl,indeno[1,2-9]anthrene, thiophenoindenyl, thiophenofluorenyl,hydrogenated versions thereof (e.g., 4,5,6,7-tetrahydroindenyl, or“H₄Ind”), substituted versions thereof, and heterocyclic versionsthereof. In a particular embodiment, the metallocenes useful in thepresent invention may be selected from those including one or two (two,in a more particular embodiment), of the same or different Cp ringsselected from the group consisting of cyclopentadienyl, indenyl,fluorenyl, tetrahydroindenyl, and substituted versions thereof.

The metal atom “M” of the metallocene catalyst compound, as describedthroughout the specification and claims, may be selected from the groupconsisting of Groups 3 through 12 atoms and lanthanide Group atoms inone embodiment; and selected from the group consisting of Groups 3through 10 atoms in a more particular embodiment, and selected from thegroup consisting of Sc, Ti, Zr, Hf, V, Nb, Ta, Mn, Re, Fe, Ru, Os, Co,Rh, Ir, and Ni in yet a more particular embodiment; and selected fromthe group consisting of Groups 4, 5, and 6 atoms in yet a moreparticular embodiment, and from Ti, Zr, Hf atoms in yet a moreparticular embodiment, and may be Zr in yet a more particularembodiment. The oxidation state of the metal atom “M” may range from 0to +7 in one embodiment; and in a more particular embodiment, is +1, +2,+3, +4 or +5; and in yet a more particular embodiment is +2, +3 or +4.The groups bound to the metal atom “M” are such that the compoundsdescribed below in the formulas and structures are electrically neutral,unless otherwise indicated. The Cp ligand(s) form at least one chemicalbond with the metal atom “M” to form the “metallocene catalystcompound”. The Cp ligands are distinct from the leaving groups bound tothe catalyst compound in that they are not highly susceptible tosubstitution/abstraction reactions.

In one aspect of the invention, the one or more metallocene catalystcomponents of the invention are represented by the formula (I):Cp^(A)Cp^(B)MX_(n) wherein M is as described above; each X is chemicallybonded to M; each Cp group is chemically bonded to M; and n is 0, 1, 2,3, or 4, and either 1 or 2 in a particular embodiment. The ligandsrepresented by Cp^(A) and Cp^(B) in formula (I) may be the same ordifferent cyclopentadienyl ligands or ligands isolobal tocyclopentadienyl, either or both of which may contain heteroatoms andeither or both of which may be substituted by a group R. In oneembodiment, Cp^(A) and Cp^(B) are independently selected from the groupconsisting of the group consisting of cyclopentadienyl, indenyl,tetrahydroindenyl, fluorenyl, and substituted derivatives of each.Independently, each Cp^(A) and Cp^(B) of formula (I) may beunsubstituted or substituted with any one or combination of substituentgroups R. Non-limiting examples of substituent groups R as used informula (I) as well as ring substituents in formulas (Va-d) includegroups selected from the group consisting of hydrogen radicals, alkyls,alkenyls, alkynyls, cycloalkyls, aryls, acyls, aroyls, alkoxys,aryloxys, alkylthiols, dialkylamines, alkylamidos, alkoxycarbonyls,aryloxycarbonyls, carbomoyls, alkyl- and dialkyl-carbamoyls, acyloxys,acylaminos, aroylaminos, and combinations thereof. More particularnon-limiting examples of alkyl substituents R associated with formula(I) through (V) include methyl, ethyl, propyl, butyl, pentyl, hexyl,cyclopentyl, cyclohexyl, benzyl, phenyl, methylphenyl, tert-butylphenylgroups, and the like, including all their isomers, for exampletertiary-butyl, isopropyl, and the like. Other possible radicals includesubstituted alkyls and aryls, such as, for example, fluoromethyl,fluoroethyl, difluoroethyl, iodopropyl, bromohexyl, chlorobenzyl, andhydrocarbyl substituted organometalloid radicals includingtrimethylsilyl, trimethylgermyl, methyldiethylsilyl, and the like;halocarbyl-substituted organometalloid radicals includingtris(trifluoromethyl)silyl, methylbis(difluoromethyl)silyl,bromomethyldimethylgermyl, and the like; disubstituted boron radicalsincluding dimethylboron, for example; and disubstituted Group 15radicals including dimethylamine, dimethylphosphine, diphenylamine,methylphenylphosphine, Group 16 radicals including methoxy, ethoxy,propoxy, phenoxy, methylsulfide, and ethylsulfide. Other substituents Rinclude olefins, such as, but not limited to, olefinically-unsaturatedsubstituents including vinyl-terminated ligands, for example 3-butenyl,2-propenyl, 5-hexenyl, and the like. In one embodiment, at least two Rgroups (two adjacent R groups in one embodiment) are joined to form aring structure having from 3 to 30 atoms selected from the groupconsisting of carbon, nitrogen, oxygen, phosphorous, silicon, germanium,aluminum, boron, and combinations thereof. Also, a substituent group Rgroup, such as 1-butanyl, may form a bonding association to the elementM.

Non-limiting examples of X groups include alkyls, amines, phosphines,ethers, carboxylates, dienes, hydrocarbon radicals having from 1 to 20carbon atoms; fluorinated hydrocarbon radicals (e.g., —C₆F₅(pentafluorophenyl)), fluorinated alkylcarboxylates (e.g., CF₃C(O)O—),hydrides and halogen ions (such as chlorine or bromine) and combinationsthereof. Other examples of X ligands include alkyl groups, such ascyclobutyl, cyclohexyl, methyl, heptyl, tolyl, trifluoromethyl,tetramethylene, pentamethylene, methylidene, methoxy, ethoxy, propoxy,phenoxy, bis(N-methylanilide), dimethylamide, dimethylphosphideradicals, and the like. In one embodiment, two or more X's form a partof a fused ring or ring system.

In another aspect of the invention, the metallocene catalyst componentincludes those of formula (I) where Cp^(A) and Cp^(B) are bridged toeach other by at least one bridging group, (A), such that the structureis represented by formula (II): Cp^(A)(A)Cp^(B)MX_(n). These bridgedcompounds represented by formula (II) are known as “bridgedmetallocenes”. Cp^(A), Cp^(B), M, X, and n in formula (II) are asdefined above for formula (I); and wherein each Cp ligand is chemicallybonded to M, and (A) is chemically bonded to each Cp. Non-limitingexamples of bridging group (A) include divalent hydrocarbon groupscontaining at least one Group 13 to 16 atom, such as, but not limitedto, at least one of a carbon, oxygen, nitrogen, silicon, aluminum,boron, germanium, tin atom, and combinations thereof wherein theheteroatom also may be C₁ to C₁₂ alkyl or aryl substituted to satisfyneutral valency. The bridging group (A) also may contain substituentgroups R as defined above (for formula (I)) including halogen radicalsand iron. More particular non-limiting examples of bridging group (A)are represented by C₁ to C₆ alkylenes, substituted C₁ to C₆ alkylenes,oxygen, sulfur, R′₂C═, R′₂Si═, —Si(R)₂Si(R′₂)—, R′₂Ge═, R′P═ (wherein“═” represents two chemical bonds), where R′ is independently selectedfrom the group consisting of hydride, hydrocarbyl, substitutedhydrocarbyl, halocarbyl, substituted halocarbyl, hydrocarbyl-substitutedorganometalloid, halocarbyl-substituted organometalloid, disubstitutedboron, disubstituted Group 15 atoms, substituted Group 16 atoms, andhalogen radical; and wherein two or more R′ may be joined to form a ringor ring system. In one embodiment, the bridged metallocene catalystcomponent of formula (II) has two or more bridging groups (A).

Other non-limiting examples of bridging group (A) include methylene,ethylene, ethylidene, propylidene, isopropylidene, diphenylmethylene,1,2-dimethylethylene, 1,2-diphenylethylene, 1,1,2,2-tetramethylethylene,dimethylsilyl, diethylsilyl, methyl-ethylsilyl,trifluoromethylbutylsilyl, bis(trifluoromethyl)silyl, di(n-butyl)silyl,di(n-propyl)silyl, di(i-propyl)silyl, di(n-hexyl)silyl,dicyclohexylsilyl, diphenylsilyl, cyclohexylphenylsilyl,t-butylcyclohexylsilyl, di(t-butylphenyl)silyl, di(p-tolyl)silyl, andthe corresponding moieties wherein the Si atom is replaced by a Ge or aC atom, dimethylsilyl, diethylsilyl, dimethylgermyl, and diethylgermyl.

In another embodiment, bridging group (A) also may be cyclic,comprising, for example 4 to 10 ring members (5 to 7 ring members in amore particular embodiment). The ring members may be selected from theelements mentioned above, from one or more of B, C, Si, Ge, N, and O ina particular embodiment. Non-limiting examples of ring structures whichmay be present as or part of the bridging moiety are cyclobutylidene,cyclopentylidene, cyclohexylidene, cycloheptylidene, cyclooctylidene,and the corresponding rings where one or two carbon atoms are replacedby at least one of Si, Ge, N, and O (in particular, Si and Ge). Thebonding arrangement between the ring and the Cp groups may be eithercis-, trans-, or a combination.

The cyclic bridging groups (A) may be saturated or unsaturated and/ormay carry one or more substituents and/or may be fused to one or moreother ring structures. If present, the one or more substituents areselected from the group consisting of hydrocarbyl (e.g., alkyl, such asmethyl) and halogen (e.g., F, Cl) in one embodiment. The one or more Cpgroups to which the above cyclic bridging moieties may optionally befused may be saturated or unsaturated, and may be selected from thegroup consisting of those having 4 to 10 (more particularly 5, 6, or 7)ring members (selected from the group consisting of C, N, O, and S in aparticular embodiment) such as, for example, cyclopentyl, cyclohexyl,and phenyl. Moreover, these ring structures may themselves be fused,such as, for example, in the case of a naphthyl group. Moreover, these(optionally fused) ring structures may carry one or more substituents.Illustrative, non-limiting examples of these substituents arehydrocarbyl (particularly alkyl) groups and halogen atoms.

The ligands Cp^(A) and Cp^(B) of formulae (I) and (II) are differentfrom each other in one embodiment, and the same in another embodiment.

In yet another aspect of the invention, the metallocene catalystcomponents include bridged mono-ligand metallocene compounds (e.g., monocyclopentadienyl catalyst components). In this embodiment, the at leastone metallocene catalyst component is a bridged “half-sandwich”metallocene represented by the formula (III): Cp^(A)(A)QMX_(n) whereinCp^(A) is defined above and is bound to M; (A) is a bridging groupbonded to Q and Cp^(A); and wherein an atom from the Q group is bondedto M; and n is an integer 0, 1, or 2. In formula (III) above, Cp^(A),(A) and Q may form a fused ring system. The X groups and n of formula(III) are as defined above in formula (I) and (II). In one embodiment,Cp^(A) is selected from the group consisting of cyclopentadienyl,indenyl, tetrahydroindenyl, fluorenyl, substituted versions thereof, andcombinations thereof. In formula (III), Q is a heteroatom-containingligand in which the bonding atom (the atom that is bonded with the metalM) is selected from the group consisting of Group 15 atoms and Group 16atoms in one embodiment, and selected from the group consisting ofnitrogen, phosphorus, oxygen, or sulfur atom in a more particularembodiment, and nitrogen and oxygen in yet a more particular embodiment.Non-limiting examples of Q groups include alkylamines, arylamines,mercapto compounds, ethoxy compounds, carboxylates (e.g., pivalate),carbamates, azenyl, azulene, pentalene, phosphoyl, phosphinimine,pyrrolyl, pyrozolyl, carbazolyl, borabenzene, and other compoundscomprising Group 15 and Group 16 atoms capable of bonding with M.

In yet another aspect of the invention, the at least one metallocenecatalyst component may be an unbridged “half sandwich” metallocenerepresented by the formula (IVa):

Cp^(A)MQ_(q)X_(n)  (IVa)

wherein Cp^(A) is defined as for the Cp groups in (I) and is a ligandthat is bonded to M; each Q is independently bonded to M; X is a leavinggroup as described above in (I); n ranges from 0 to 3, and is 0 or 3 inone embodiment; q ranges from 0 to 3; and is 0 or 3 in one embodiment.In one embodiment, Cp^(A) is selected from the group consisting ofcyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, substitutedversion thereof, and combinations thereof. In formula (IVa), Q isselected from the group consisting of ROO⁻, RO—, R(O)—, —NR—, —CR₂—,—S—, —NR₂, —CR₃, —SR, —SiR₃, —PR₂, —H, and substituted and unsubstitutedaryl groups, wherein R is selected from the group consisting of C₁ to C₆alkyls, C₆ to C₁₂ aryls, C₁ to C₆ alkylamines, C₆ to C₁₂alkylarylamines, C₁ to C₆ alkoxys, C₆ to C₁₂ aryloxys, and the like.Non-limiting examples of Q include C₁ to C₁₂ carbamates, C₁ to C₁₂carboxylates (e.g., pivalate), C₂ to C₂₀ alkyls, and C₂ to C₂₀heteroallyl moieties.

In another aspect of the invention, the metallocene catalyst componentis one or more as described in U.S. Pat. Nos. 5,703,187, and 5,747,406,including a dimer or oligomeric structure, such as disclosed in, forexample, U.S. Pat. Nos. 5,026,798 and 6,069,213. In another aspect ofthe invention, the metallocene catalyst component is one or more asdescribed in U.S. Pat. No. 6,069,213.

It is contemplated that the metallocene catalyst components describedabove include their structural or optical or enantiomeric isomers(racemic mixture), and may be a pure enantiomer in one embodiment. Asused herein, a single, bridged, asymmetrically substituted metallocenecatalyst component having a racemic and/or meso isomer does not, itself,constitute at least two different bridged, metallocene catalystcomponents. The “metallocene catalyst component” useful in the presentinvention may comprise any combination of any embodiment describedherein.

In addition to the catalyst component described above, the catalystsystem employed in the present process employs an activator preferablyselected from alumoxanes, such as methyl alumoxane, modified methylalumoxane, ethyl alumoxane, iso-butyl alumoxane, and the like; neutralactivators, such as triphenyl boron, tris-perfluorophenyl boron,tris-perfluoronaphthylboron, tris-perfluorophenyl aluminum, and thelike; and ionic activators, such as N,N-dimethylanilinium tetrakisperfluorophenyl borate, triphenyl carbonium tetrakis perfluorophenylborate, N,N-dimethylanilinium tetrakis perfluoronaphthyl borate,N,N-dimethylanilinium tetrakis perfluorophenyl aluminate, and the like.

A co-activator is a compound capable of alkylating the transition metalcomplex, such that when used in combination with an activator, an activecatalyst is formed. Co-activators include alumoxanes, such as methylalumoxane; modified alumoxanes, such as modified methyl alumoxane; andaluminum alkyls, such as trimethyl aluminum, tri-isobutyl aluminum,triethyl aluminum, and tri-isopropyl aluminum. Co-activators aretypically only used in combination with neutral activators and ionicactivators when the pre-catalyst is not a dihydrocarbyl or dihydridecomplex.

The alumoxane component useful as an activator typically is anoligomeric aluminum compound represented by the general formula(R^(x)—Al—O)_(n), which is a cyclic compound, orR^(x)(R^(x)—Al—O)—AlR^(x) ₂, which is a linear compound. In the generalalumoxane formula, R^(x) is independently a C₁-C₂₀ alkyl radical, forexample methyl, ethyl, propyl, butyl, pentyl, isomers thereof, and thelike, and “n” is an integer from 1-50. Most preferably, R^(x) is methyland “n” is at least 4. Methyl alumoxane and modified methyl alumoxanesare most preferred. For further descriptions see, EP 0 279 586; EP 0 594218; EP 0 561 476; WO94/10180; and U.S. Pat. Nos. 4,665,208; 4,874,734;4,908,463; 4,924,018; 4,952,540; 4,968,827; 5,041,584; 5,091,352;5,103,031; 5,157,137; 5,204,419; 5,206,199; 5,235,081; 5,248,801;5,329,032; 5,391,793; and 5,416,229.

When an alumoxane or modified alumoxane is used, the pre-catalyst (allpre-catalysts)-to-activator molar ratio is from about 1:3000-10:1;alternatively, 1:2000-10:1; alternatively 1:1000-10:1; alternatively,1:500-1:1; alternatively 1:300-1:1; alternatively 1:200-1:1;alternatively 1:100-1:1; alternatively 1:50-1:1; alternatively 1:10-1:1.When the activator is an alumoxane (modified or unmodified), someembodiments select the maximum amount of activator at a 5000-fold molarexcess over the pre-catalyst (per metal catalytic site). The preferredminimum activator-to-pre-catalyst-ratio is 1:1 molar ratio.

NCA activators (at times used in combination with a co-activator) may beused in the practice of this invention. Preferably, discrete ionicactivators such as [Me₂PhNH][B(C₆F₅)₄], [Ph₃C][B(C₆F₅)₄],[Me₂PhNH][B((C₆H₃-3,5-(CF₃)₂))₄], [Ph₃C][B((C₆H₃-3,5-(CF₃)₂))₄],[NH₄][B(C₆H₅)₄], [Me₂PhNH][B(C₁₀F₇)₄], [Ph₃C][B(C₁₀F₇)₄], or neutralactivators, such as B(C₆F₅)₃, B(C₁₀F₇)₃, or B(C₆H₅)₃ can be used (whereC₆F₅ is perfluorophenyl, C₁₀F₇ is perfluoronaphthyl, and C₆H₃-3,5-(CF₃)₂is 3,5-bis(trifluoromethyl)phenyl). Preferred co-activators, when used,are alumoxanes, such as methyl alumoxane, modified alumoxanes, such asmodified methyl alumoxane, and aluminum alkyls, such as tri-isobutylaluminum, and trimethyl aluminum.

It is within the scope of this invention to use one or more type of NCAactivators, which may be neutral or ionic, such as tri (n-butyl)ammonium tetrakis (pentafluorophenyl) borate, a trisperfluorophenylboron metalloid precursor, or a trisperfluoronaphthyl boron metalloidprecursor, polyhalogenated heteroborane anions (WO 98/43983), boric acid(U.S. Pat. No. 5,942,459).

Activated ionic catalysts can be prepared by reacting a transition metalcompound (pre-catalyst) with a neutral activator, such as B(C₆F₆)₃,which upon reaction with the hydrolyzable ligand (X) of the transitionmetal compound forms an anion, such as ([B(C₆F₅)₃(X)]⁻), whichstabilizes the cationic transition metal species generated by thereaction.

Examples of neutral NCA activators include tri-substituted boron,tellurium, aluminum, gallium and indium or mixtures thereof. The threesubstituent groups are each independently selected from alkyls,alkenyls, halogen, substituted alkyls, aryls, arylhalides, alkoxy, andhalides. Preferably, the three groups are independently selected fromhalogen, mono or multicyclic (including halosubstituted) aryls, alkyls,and alkenyl compounds and mixtures thereof, preferred are alkenyl groupshaving 1-20 carbon atoms, alkyl groups having 1-20 carbon atoms, alkoxygroups having 1-20 carbon atoms and aryl groups having 3-20 carbon atoms(including substituted aryls). More preferably, the three groups arealkyls having 1-4 carbon groups, phenyl, naphthyl, or mixtures thereof.Even more preferably, the three groups are halogenated, preferablyfluorinated, aryl groups. Most preferably, the neutral NCA activator istrisperfluorophenyl boron or trisperfluoronaphthyl boron.

Ionic NCA activator compounds may contain an active proton, or someother cation associated with, but not coordinated to, or only looselycoordinated to, the remaining ion of the ionizing compound. Suchcompounds and the like are described in European publications EP 0 570982 A; EP 0 520 732 A; EP 0 495 375 A; EP 0 500 944 B1; EP 0 277 003 A;EP 0 277 004 A; U.S. Pat. Nos. 5,153,157; 5,198,401; 5,066,741;5,206,197; 5,241,025; 5,384,299; 5,502,124; and U.S. Ser. No.08/285,380, filed Aug. 3, 1994, all of which are herein fullyincorporated by reference. In this case, the ionic activator reacts withthe transition metal compound (pre-catalyst) to form a cationictransition metal species, an anion, and byproduct(s). The byproducts aredefined by the cation associated with the ionic NCA activator used.

Compounds useful as an ionic NCA activator comprise a cation, which ispreferably a Bronsted acid capable of donating a proton, and acompatible non-coordinating anion which anion is relatively large(bulky), capable of stabilizing the active catalyst species which isformed when the two compounds are combined and said anion will besufficiently labile to be displaced by olefinic diolefinic andacetylenically unsaturated substrates or other neutral Lewis bases, suchas ethers, nitriles, and the like. Two classes of compatiblenon-coordinating anions have been disclosed in EP 0 277 003 A and EP 0277 004 A, published 1988: 1) anionic coordination complexes comprisinga plurality of lipophilic radicals covalently coordinated to andshielding a central charge-bearing metal or metalloid core; and 2)anions comprising a plurality of boron atoms such as carboranes,metallacarboranes, and boranes.

In a preferred embodiment, the ionic NCA activators include a cation andan anion component, and may be represented by the following formula:

(L**−H)_(d) ⁺(A^(d−))

wherein L** is a neutral Lewis base; H is hydrogen; (L**−H)⁺ is aBronsted acid; A^(d−) is a non-coordinating anion having the charge d−;d is 1, 2, or 3.

The cation component, (L**−H)_(d) ⁺ may include Bronsted acids such asprotons or protonated Lewis bases or reducible Lewis acids capable ofprotonating or abstracting a moiety, such as an alkyl or aryl, from thepre-catalyst after alkylation.

The activating cation (L**−H)_(d) ⁺ may be a Bronsted acid, capable ofdonating a proton to the alkylated transition metal catalytic precursorresulting in a transition metal cation, including ammoniums, oxoniums,phosphoniums, silyliums, and mixtures thereof; preferably ammoniums ofmethylamine, aniline, dimethylamine, diethylamine, N-methylaniline,diphenylamine, trimethylamine, triethylamine, N,N-dimethylaniline,methyldiphenylamine, pyridine, p-bromo N,N-dimethylaniline,p-nitro-N,N-dimethylaniline; phosphoniums from triethylphosphine,triphenylphosphine, and diphenylphosphine; oxomiuns from ethers, such asdimethyl ether, diethyl ether, tetrahydrofuran, and dioxane; sulfoniumsfrom thioethers, such as diethyl thioethers and tetrahydrothiophene, andmixtures thereof. The activating cation (L**−H)_(d) ⁺ may also be amoiety, such as silver, tropylium, carbeniums, ferroceniums, andmixtures; preferably carboniums and ferroceniums; most preferablytriphenyl carbonium.

The anion component A^(d−) include those having the formula[M^(k+)Q_(n)]^(d−) wherein k is an integer from 1-3; n is an integerfrom 2-6; n−k=d; M is an element selected from group 13 of the PeriodicTable of the Elements, preferably boron or aluminum; and Q isindependently a hydride, bridged or unbridged dialkylamido, halide,alkoxide, aryloxide, hydrocarbyl, substituted hydrocarbyl, halocarbyl,substituted halocarbyl, and halosubstituted-hydrocarbyl radicals, said Qhaving up to 20 carbon atoms with the proviso that in not more than oneoccurrence is Q a halide. Preferably, each Q is a fluorinatedhydrocarbyl having 1-20 carbon atoms, more preferably each Q is afluorinated aryl group, and most preferably each Q is a pentafluorylaryl group. Examples of suitable A^(d−) also include diboron compoundsas disclosed in U.S. Pat. No. 5,447,895, which is fully incorporatedherein by reference.

Most preferably, the ionic NCA activator is N,N-dimethylaniliniumtetrakis(perfluorophenyl)borate, N,N-dimethylaniliniumtetrakis(perfluoronaphthyl)borate, N,N-dimethylaniliniumtetrakis(perfluorobiphenyl)borate, N,N-dimethylaniliniumtetrakis(3,5-bis(trifluoromethyl)phenyl)borate, triphenylcarbeniumtetrakis(perfluoronaphthyl)borate, triphenylcarbeniumtetrakis(perfluorobiphenyl)borate, triphenylcarbeniumtetrakis(3,5-bis(trifluoromethyl)phenyl)borate, or triphenylcarbeniumtetra(perfluorophenyl)borate.

The catalyst precursors employed in the present process can also beactivated with cocatalysts or activators that comprise non-coordinatinganions containing metalloid-free cyclopentadienide ions. These aredescribed in U.S. Patent Publication 2002/0058765 A1, published on 16May 2002, and for the instant invention, require the addition of aco-activator to the catalyst pre-cursor.

The term “non-coordinating anion” (NCA) means an anion that does notcoordinate to the catalyst metal cation or that does coordinate to themetal cation, but only weakly. An NCA coordinates weakly enough that aneutral Lewis base, such as an olefinically or acetylenicallyunsaturated monomer can displace it from the catalyst center.“Compatible” non-coordinating anions are those which are not degraded toneutrality when the initially formed complex decomposes. Further, theanion will not transfer an anionic substituent or fragment to the cationso as to cause it to form a neutral transition metal compound and aneutral by-product from the anion. Non-coordinating anions useful inaccordance with this invention are those that are compatible, stabilizethe transition metal complex cation in the sense of balancing its ioniccharge at +1, and yet retain sufficient liability to permit displacementby an ethylenically or acetylenically unsaturated monomer duringpolymerization. These types of cocatalysts sometimes use scavengers,such as, but not limited to, tri-iso-butyl aluminum, tri-n-octylaluminum, tri-n-hexyl aluminum, triethylaluminum, or trimethylaluminum.

The present process also can employ cocatalyst compounds or activatorcompounds that are initially neutral Lewis acids but form a cationicmetal complex and a noncoordinating anion, or a zwitterionic complexupon reaction with the alkylated transition metal compounds. Thealkylated transition metal compound is formed from the reaction of thecatalyst pre-cursor and the co-activator. For example,tris(pentafluorophenyl) boron or aluminum act to abstract a hydrocarbylligand to yield an invention cationic transition metal complex andstabilizing noncoordinating anion, see EP 0 427 697 A and EP 0 520 732 Afor illustrations of analogous group 4 metallocene compounds. Also, seethe methods and compounds of EP 0 495 375 A. For formation ofzwitterionic complexes using analogous Group 4 compounds, see U.S. Pat.Nos. 5,624,878; 5,486,632; and 5,527,929.

Additional neutral Lewis-acids are known in the art and are suitable forabstracting formal anionic ligands. See in particular the review articleby E. Y.-X. Chen and T. J. Marks, “Cocatalysts for Metal-CatalyzedOlefin Polymerization: Activators, Activation Processes, andStructure-Activity Relationships”, Chem. Rev., 100, pp. 1391-1434(2000).

When the cations of noncoordinating anion precursors are Bronsted acids,such as protons or protonated Lewis bases (excluding water), orreducible Lewis acids, such as ferrocenium or silver cations, or alkalior alkaline earth metal cations, such as those of sodium, magnesium, orlithium, the catalyst-precursor-to-activator molar ratio may be anyratio. Combinations of the described activator compounds may also beused for activation.

When an NCA activator is used, the pre-catalyst (allpre-catalysts)-to-activator molar ratio is from 1:10-1:1; 1:10-10:1;1:10-2:1; 1:10-3:1; 1:10-5:1; 1:2-1.2:1; 1:2-10:1; 1:2-2:1; 1:2-3:1;1:2-5:1; 1:3-1.2:1; 1:3-10:1; 1:3-2:1; 1:3-3:1; 1:3-5:1; 1:5-1:1;1:5-10:1; 1:5-2:1; 1:5-3:1; 1:5-5:1; 1:1-1:1.2. Thepre-catalyst-to-co-activator molar ratio is from 1:100-100:1; 1:75-75:1;1:50-50:1; 1:25-25:1; 1:15-15:1; 1:10-10:1; 1:5-5:1, 1:2-2:1; 1:100-1:1;1:75-1:1; 1:50-1:1; 1:25-1:1; 1:15-1:1; 1:10-1:1; 1:5-1:1; 1:2-1:1;1:10-2:1.

Preferred activators and activator/co-activator combinations includemethylalumoxane, modified methylalumoxane, mixtures of methylalumoxanewith dimethylanilinium tetrakis(pentafluorophenyl)borate ortris(pentafluorophenyl)boron, and mixtures of trimethyl aluminum ortriethyl aluminum or triisobutyl aluminum or tri-n-octylaluminum withdimethylanilinium tetrakis(pentafluorophenyl)borate ortris(pentafluorophenyl)boron or dimethylaniliniumtetrakis(perfluoronaphthyl)borate. Particularly preferredactivator/co-activator combinations include tri-n-octylaluminum withdimethylanilinium tetrakis(pentafluorophenyl)borate, tri-n-octylaluminumwith dimethylanilinium tetrakis(perfluoronaphthyl)borate, andmethylalumoxane with dimethylaniliniumtetrakis(pentafluorophenyl)borate.

In some embodiments, scavenging compounds are used with NCA activators.Typical aluminum or boron alkyl components useful as scavengers arerepresented by the general formula R^(x)JZ₂ where J is aluminum orboron, R^(x) is a C₁-C₂₀ alkyl radical, for example, methyl, ethyl,propyl, butyl, pentyl, isomers thereof, and each Z is independentlyR^(x) or a different univalent anionic ligand, such as halogen (Cl, Br,I), alkoxide (OR^(x)), and the like. Most preferred aluminum alkylsinclude triethylaluminum, diethylaluminum chloride,tri-iso-butylaluminum, tri-n-octylaluminum. tri-n-hexylaluminum,trimethylaluminum, and the like. Preferred boron alkyls includetriethylboron. Scavenging compounds may also be alumoxanes and modifiedalumoxanes including methylalumoxane and modified methylalumoxane.

The catalyst system useful in the present invention may further comprisea support material. Supports, methods of supporting, modifying, andactivating supports for single-site catalyst, such as metallocenes, isdiscussed in, for example, 1 METALLOCENE-BASED POLYOLEFINS, pp. 173-218(J. Scheirs & W. Kaminsky eds., John Wiley & Sons, Ltd. 2000). Desirablecarriers are inorganic oxides that include Group 2, 3, 4, 5, 13, and 14oxides and chlorides in one embodiment, and more particularly, inorganicoxides and chlorides of Group 13 and 14 atoms. Yet more particularly,support materials include silica, alumina, silica-alumina, magnesiumchloride, graphite, and mixtures thereof. Other useful supports includemagnesia, titania, zirconia, montmorillonite (EP 0 511 665 B1),phyllosilicate, and the like. Also, combinations of these supportmaterials may be used, for example, silica-chromium, silica-alumina,silica-titania, and the like. Additional support materials may includethose porous acrylic polymers described in EP 0 767 184 B1.

In certain embodiment, the two catalyst components reside on a singlesupport particles. Alternatively, each catalyst can be supported ondifferent support particles.

The in-reactor blends described herein are used as modifiers of linearethylene containing polymers and are blended with at least one linearethylene polymer to prepare the compositions of this invention.

Additives

The composition of this invention may optionally be combined with one ormore polymer additives known in the art, such as reinforcing andnon-reinforcing fillers, scratch resistant agents, plasticizers,antioxidants, heat stabilizers, extender oils, lubricants, antiblockingagents, antistatic agents, anti-fogging agent, waxes, foaming agents,pigments, flame/fire retardants, dyes and colorants, and ultravioletabsorber. Other additives include, for example, blowing agents,vulcanizing or curative agents, vulcanizing or curative accelerators,cure retarders, processing aids, tackifying resins, and other processingaids known in the polymer compounding art. The lists described hereinare not intended to be inclusive of all types of additives which may beemployed with the present invention. Upon reading this disclosure, thoseof skilled in the art will appreciate other additives may be employed toenhance properties. As is understood by the skilled in the art, theblends of the present invention may be modified to adjust thecharacteristics of the blends as desired. The aforementioned additivesmay be either added independently or incorporated into an additive ormasterbatch. Such additives may comprise up to about 70 wt %, morepreferably up to about 65 wt %, of the total composition.

The compositions of this invention may also comprise slip agents ormold-release agents to facilitate moldability, preferably present at 50ppm to 10 wt %, more preferably 50 ppm to 5000 ppm, even more preferably0.01 wt % to 0.5 wt % (100 ppm to 5000 ppm), even more preferably 0.1 wt% to 0.3 wt % (1000 ppm to 3000 ppm), based upon the weight of thecomposition. Desirable slip additives include but are not limited tosaturated fatty acid amides (such as palmitamide, stearamide,arachidamide, behenamide, stearyl stearamide, palmityl pamitamide, andstearyl arachidamide); saturated ethylene-bis-amides (such asstearamido-ethyl-stearamide, stearamido-ethyl-palmitamide, andpalmitamido-ethyl-stearamide); unsaturated fatty acid amides (such asoleamide, erucamide, and linoleamide); unsaturated ethylene-bis-amides(such as ethylene-bis-stearamide, ethylene-bis-oleamide,stearyl-erucamide, erucamido-ethyl-erucamide, oleamido-ethyl-oleamide,erucamido-ethyl-oleamide, oleamido-ethyl-lerucamide,stearamido-ethyl-erucamide, erucamido-ethyl-palmitamide, andpalmitamido-ethyl-oleamide); glycols; polyether polyols (such asCarbowax); acids of aliphatic hydrocarbons (such as adipic acid andsebacic acid); esters of aromatic or aliphatic hydrocarbons (such asglycerol monostearate and pentaerythritol monooleate);styrene-alpha-methyl styrene; fluoro-containing polymers (such aspolytetrafluoroethylene, fluorine oils, and fluorine waxes); siliconcompounds (such as silanes and silicone polymers, including siliconeoils, modified silicones and cured silicones); sodium alkylsulfates,alkyl phosphoric acid esters; stearates (such as zinc stearate); andmixtures thereof. Preferred slip additives are unsaturated fatty acidamides, which are available from Crompton (Kekamide™ grades) and CrodaUniversal (Crodamide™ grades). Particularly preferred are the erucamideand oleamide versions of unsaturated fatty acid amides. Preferred slipagents also include amides having the chemical structureCH₃(CH₂)₇CH═CH(CH₂)_(x)CONH₂ where x is 5 to 15. Particularly preferredamides include: 1) Erucamide CH₃(CH₂)₇CH═CH(CH₂)₁₁CONH₂ which may alsobe referred to as cis-13-docosenoamide (Erucamide is commerciallyavailable from Akzo Nobel Amides Co. Ltd. under the trade name ARMOSLIPE); 2) Oleylamide CH₃(CH₂)₇CH═CH(CH₂)₈CONH₂; and 3) Oleamide which mayalso be preferred to as N-9-octadecenyl-hexadecanamide)CH₃(CH₂)₇CH═CH(CH₂)₇CONH₂. In another embodiment, stearamide is alsouseful in this invention. Other preferred slip additives include thosedescribed in WO 2004/005601A1.

Additional polymers can also be added into the inventive compositions.In one or more embodiments, the additional polymers includethermoplastic resins or thermoplastic elastomers. Exemplarythermoplastic resins include crystalline polyolefins, such aspolypropylene and impact copolymers. Also, suitable thermoplastic resinsmay include copolymers of polyolefins with styrene, such as astyrene/ethylene copolymer. In one or more embodiments, thethermoplastic resins are formed by polymerizing ethylene oralpha-olefins, such as propylene, 1-butene, 1-hexene, 1-octene,2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene,5-methyl-1-hexene, and mixtures thereof. Copolymers of ethylene andpropylene and ethylene and propylene with another alpha-olefin, such as1-butene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1-pentene,4-methyl-1-pentene, 5-methyl-1-hexene, or mixtures thereof, are alsocontemplated. Specifically included are the homopolypropylene, impact,and random copolymers of propylene with ethylene or the higheralpha-olefins. Preferably, the homopolypropylene has a melting point ofat least 130° C., for example at least 140° C. and preferably less thanor equal to 170° C., a heat of fusion of at least 75 J/g, alternativelyat least 80 J/g, as determined by DSC analysis, and weight averagemolecular weight (M_(w)) of at least 50,000, alternatively at least100,000 g/mol. Comonomer contents for these propylene copolymers willtypically be from 1% to about 30% by weight of the polymer (See, forexample, U.S. Pat. Nos. 6,268,438; 6,288,171; and 6,245,856). Copolymersavailable under the trade name VISTAMAXX™ (ExxonMobil, Houston, Tex.)are specifically included. Blends or mixtures of two or more polyolefinthermoplastics such as described herein, or with other polymericmodifiers, are also suitable in accordance with this invention. Thesehomopolymers and copolymers may be synthesized by using an appropriatepolymerization technique known in the art, such as, but not limited to,the conventional Ziegler-Natta type polymerizations, and catalysisemploying single-site organometallic catalysts including, but notlimited to, metallocene catalysts.

The compositions of this invention (comprising a linear ethylenecontaining polymer and an in-reactor blend) preferably have one or moreof the following properties:

-   -   a) a decrease in the viscoelastic phase angle (δ) at a complex        modulus of 10 kPa at 190° C. (as described in the Examples        section below) of at least 0.3° per wt % of the in-reactor        polymer blend added relative to the linear ethylene containing        polymer; and/or    -   b) an increase in the degree of shear thinning at 190° C. (as        described in the Examples section below) of at least 0.002 per        wt % of the in-reactor polymer blend added relative to the        linear ethylene containing polymer; and/or    -   c) a Young's Modulus (modified ASTM D 638) of at least 250 MPa        or more (preferably 300 MPa or more, preferably 350 MPa or        more); and/or    -   d) strain at yield (modified ASTM D 638) of at least 2% or more        (preferably 4% or more, preferably 5% or more); and/or    -   e) stress at yield (modified ASTM D 638) of at least 5 MPa or        more (preferably 7 MPa or more, preferably 9 MPa or more);        and/or    -   f) stress at 100% strain (modified ASTM D 638) of at least 5 MPa        or more (preferably 7 MPa or more, preferably 10 MPa or more);        and/or    -   g) strain at break (modified ASTM D 638) of at least 150% or        more (preferably 200% or more, preferably 230% or more); and/or    -   h) stress at break (modified ASTM D 638) of at least 15 MPa or        more (preferably 20

MPa or more, preferably 22 MPa or more); and/or

-   -   i) toughness (determined as described in the Examples section)        of at least 25 MJ/m³ or more (preferably 30 MJ/m³ or more,        preferably 32 MJ/m³ or more).

Use of the Polymer Blends

The inventive compositions can be used in many applications wherethermoplastics are used. The inventive blends provide high meltstrength, ease of processability (shear thinning), and higherapplication temperatures over a wide range of densities. The inventivecompositions are useful in such forming operations as film, sheet, pipeand fiber extrusion, and co-extrusion, as well as blow molding,injection molding, and rotary molding. Films include blown or cast filmsformed by coextrusion or by lamination useful as shrink film, clingfilm, stretch film, sealing films, oriented films, snack packaging,heavy duty bags, grocery sacks, baked and frozen food packaging, cableand wire sheathing, medical packaging, industrial liners, membranes,etc. in food-contact and non-food contact applications. Fibers includemelt spinning, solution spinning and melt blown fiber operations for usein woven or non-woven form to make filters, diaper fabrics, medicalgarments, geotextiles, etc. Extruded articles include medical tubing,wire and cable coatings, geomembranes, and pond liners. Molded articlesinclude single and multi-layered constructions in the form of bottles,tanks, large hollow articles, rigid food containers and toys, etc.

Film blowing is the most widely used extrusion technique in terms ofpolyethylene production volume. Yearly billions of pounds of PE areprocessed by this method to produce grocery sacks and trash can liners.LLDPE's have narrower MWD's but contain no long chain branching (LCB).They have high entanglement densities which enhance film stretchability,leading to a higher resistance to damage by foreign objects to avoidtear and subsequently down time during the high-speed blowing process.However, the high entanglement density makes LLDPE viscous in the moltenstate. Also, their short chain branching (SCB) does not enhance shearthinning. Therefore, LLDPE is more viscous at high shear rates whenprocessed in the extruder and the die than LDPE, which contains acertain amount of LCB. The narrow MWD's of mLLDPEs even make them moredifficult to flow than conventional LLDPE's (znLLDPE) made byZiegler-Natta catalysis. At the same time, LLDPE's show lowerextensional stresses at low strain rates in the molten tube and bubbleinflation regions, hence more prone to bubble instability. Anotherimportant feature in film blowing is its ability to draw down the filmso that its final gauge is much thinner than the die gap. However, thisis limited by the strength of the melt in the bubble. In the case of ahigh nip roll speed, the tensile stress in the bubble will exceed thecohesive strength of the melt, leading to film rupture. Therefore, thereis always a need to improve the melt processability and the meltstrength of both mLLDPE's and Ziegler-Natta LLDPE's in the film blowingprocess. Adding an in-reactor polymer blend in a LLDPE can reduce oreliminate the above problems because the in-reactor polymer blend canslowly relax the polymer chains, leading to high zero shear viscosity,shear thinning, and melt elasticity. The long relaxation time of theLLDPE blended with the in-reactor polymer blend also produces a highmelt strength and easy processing in extruders.

More particularly, the inventive compositions are useful in makingfilms. The films may be of any desirable thickness or composition, inone embodiment from 1 to 100 microns, and from 2 to 50 microns in a moreparticular embodiment, and from 10 to 30 microns in yet a moreparticular embodiment; and comprise copolymers of ethylene with a C₃ toC₁₀ olefin in one embodiment, ethylene with C₃ to C₈ α-olefins in aparticular embodiment, and ethylene with C₄ to C₆ α-olefins in yet amore particular embodiment. The resins used to make the films may beblended with other additives such as pigments, antioxidants, fillers,etc, as is known in the art, as long as they do not interfere with thedesired film properties.

For the case of HDPE's, a high-MW polymer will yield a stronger but lessflexible film. Also, it is a challenge to achieve a good balance oforientation in the machine and transverse directions, probably due toits extensional flow properties. Incorporating an in-reactor polymerblend in HDPE's can reduce or eliminate these shortcomings.

The inventive compositions can also be used as an impact modifier ofpolypropylene. TPO compounding is the process of mixing polypropylene(PP) with other ingredients to form a PP based multi-component mixture.For typical TPO applications, the TPO mixture can have about 10% to 30%of the inventive polymer blend.

Thermoforming processes also favor the use of the high melt strength orthe high melt elasticity of polyolefins. Thermoforming is the process ofheating a solid plastic article, mostly in the sheet form, to atemperature where it softens, but does not flow, then reshaping it. Thisprocess has a large cost advantage over injection molding because ofless expensive mold and lower energy expended. However, caution to avoidthe buildup of slack in the heated sheet needs to be exercised in thethermoforming process. It has been found that a polyolefin containing acertain amount of branching can improve its melt strength or elasticity,which in turn improves its sagging resistance. Although thermoformingprocess of polyethylene (PE) is not as popular as that of polypropylene(PP), adding an in-reactor polymer blend in PE can improve the meltstrength of PE during the thermoforming process. The inventivecompositions are useful in thermoforming processes.

The inventive compositions may be used in any known applicationinvolving molding or extrusion, including consumer goods, industrialgoods, construction materials, packaging materials, and automotiveparts. The in-reactor polymer blends described herein may be molded intodesirable end use articles by any suitable means known in the art,including but not limited to, injection molding, gas-assisted injectionmolding, extrusion blow molding, injection blow molding, injectionstretch blow molding, compression molding, rotational molding, foammolding, thermoforming, sheet extrusion, and profile extrusion. Themolding processes are well known to those of ordinary skill in the art.They are particularly useful for making articles by injection molding,blow molding, film blowing, extrusion, thermoforming, gas foaming,elasto-welding, and compression molding techniques.

Blow molding is another suitable forming means, which includes injectionblow molding, multi-layer blow molding, extrusion blow molding, andstretch blow molding, and is especially suitable for substantiallyclosed or hollow objects, such as, for example, gas tanks and otherfluid containers. Blow molding is described in more detail in, forexample, CONCISE ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING, pp.90-92 (Jacqueline I. Kroschwitz, ed., John Wiley & Sons 1990).

In yet another embodiment of the formation and shaping process, profileco-extrusion can be used. The profile co-extrusion process parametersare as above for the blow molding process, except the die temperatures(dual zone top and bottom) range from 150° C. to 235° C., the feedblocks are from 90° C. to 250° C., and the water cooling tanktemperatures are from 10° C. to 40° C.

Preferred articles made using the in-reactor polymer blends includecookware, storageware, toys, medical devices, medical containers,healthcare items, sheets, crates, containers, bottles, packaging, wireand cable jacketing, pipes, sporting equipment, chair mats, tubing,profiles, instrumentation sample holders and sample windows, automotive,boat and water craft components, and other such articles. In particular,the compositions are suitable for automotive components, such as trimparts, parts for dashboards and instrument panels, mirror housing, bodypanel, protective side molding, and other interior and externalcomponents associated with automobiles, trucks, boats, and othervehicles.

The disclosed molded parts may also be fabricated using a co-injectionmolding process, whereby an injection mold is used to form the partand/or lid and the materials are co-injected into the mold to formseparate skins. Also, the part and/or lid can be fabricated using anovermolding process, whereby one of the layers is molded first and theother layers are molded over the previously molded structure.Conventional injection molding and thermal molding may also be utilized.Further, injection molding and blow molding techniques may be combinedby injection molding a preform, which is transferred to a blow mold, andinflated to form an outer structure with inner structures or layersblown into the outer structure. The process can be repeated to form asmany layers as desired.

In certain embodiments, the molded articles made of the compositions ofthe present invention are formed by thermoforming, blow molding,injection molding, compression molding, or injection-compressionmolding.

The nature of high shear thinning of the invented reactor polymer blendsprovides a number of advantages in the injection molding processes.These materials allow using multi-shot injection molding, and makingthinner and bigger pieces. It is also possible to use lower injectiontemperature for this invented in-reactor polymer blends. In addition tothe energy saving, lower injection temperature will reduce the samplecooling time and reduce the production cycle time, and make theinjection process more efficient.

In another embodiment, this invention relates to:

1. A composition comprising:

1) a linear ethylene containing polymer having a density of at least0.910 g/cm³; and

2) an in-reactor polymer blend comprising: (a) a first ethylenecontaining polymer having a density of greater than 0.90 g/cm³ and aM_(w) of more than 20,000 g/mol; and (b) a second ethylene containingpolymer having a density of less than 0.90 g/cm³, wherein the densitiesof the first and second polymers differ by at least 1%, and wherein thein-reactor polymer blend has a T_(m) of at least 90° C. (DSC secondmelt), a density of less than 0.92 g/cm³, and contains at least 78 wt %ethylene.

2. A composition comprising:

1) a linear ethylene containing polymer having a density of at least0.910 g/cm³; and

2) at least 1 wt % of an in-reactor polymer blend comprising: (a) afirst ethylene polymer comprising 90 wt % to 100 wt % ethylene and from0 wt % to less than 10 wt % comonomer, said first ethylene polymercomponent having density of greater than 0.920 g/cm³ and an M_(w) of20,000 g/mol or more; and (b) a second ethylene polymer comprising from70 wt % to 90 wt % ethylene and 30 wt % to 10 wt % comonomer, saidsecond ethylene polymer having a density of 0.910 g/cm³ or less, whereinthe in-reactor polymer blend has:

-   -   (a) at least 78 wt % ethylene;    -   (b) a T_(m) of at least 100° C. over a density ranging from 0.84        to 0.92 g/cm³;    -   (c) an elongation at break of 300% or more;    -   (d) a strain hardening ratio, M300/M100, of at least 1.2;    -   (e) a ratio of complex viscosity at 0.01 rad/s to the complex        viscosity at 100 rad/s of at least 30; and    -   (f) a shear thinning index of less than −0.2.        3. The composition of paragraph 1 or 2, wherein the difference        in density between the first ethylene polymer and the second        ethylene polymer is at least 1%.        4. The composition of paragraph 1, 2, or 3, wherein the first        ethylene polymer has a T_(m) of 110° C. or more and a melt index        at 190° C., under a 2.16 kg load, of 0.01 to 800 dg/min, and/or        the second ethylene containing polymer of the in-reactor blend        has a melt index at 190° C., under a 2.16 kg load, of 200 dg/min        or less.        5. The composition of paragraph 1, 2, 3, or 4, wherein the        in-reactor blend has a density from 0.84 to 0.92 g/cm³ and a        melting point of from 100° C. to 130° C.        6. The composition of any of paragraphs 1 to 5, wherein the        in-reactor blend has:    -   a) a strain hardening index M500/M100 of at least 1.2; and/or    -   b) a heat of fusion of at least 50 J/g; and/or    -   c) a tensile strength of greater than 15 MPa; and/or    -   d) an elongation at break of greater than 400%; and/or    -   e) a tensile toughness of 40 MJ/m³ or more; and/or    -   f) a melt index at 190° C., under a 2.16 kg load, of 0.01 to 100        dg/min; and/or    -   g) a cyclohexane refluxing insoluble fraction of 70 wt % or        less.        7. The composition of any of paragraphs 1 to 6, wherein the        first ethylene containing polymer of the in-reactor blend has 95        wt % to 100 wt % ethylene and 0 wt % to 5 wt % comonomer        selected from the group consisting of propylene, butene, hexene        or octene; and/or the second ethylene containing polymer of the        in-reactor blend has 70 wt % to 90 wt % ethylene and 10 wt % to        30 wt % comonomer selected from the group consisting of        propylene, butene, hexene or octene.        8. The composition of any of paragraphs 1 to 7, wherein second        ethylene containing polymer has a 1% secant flexural modulus        from 5 to 100 MPa.        9. The composition of any of paragraphs 1 to 8, wherein the        linear ethylene containing polymer (preferably an LLDPE or an        HDPE) preferably comprises from 50 mole % to 100 mole % ethylene        and from 0 mole % to 50 mole % of C₂ to C₄₀ comonomer and has:    -   a) a CDBI of 60% or more; and/or    -   b) an M_(w) of 50,000 g/mol or more; and/or    -   c) a g′ of 0.95 or more; and/or    -   d) an M_(w)/M_(n) of from greater than 1 to 10; and/or    -   e) a density of 0.910 to 0.940 g/cm³.        10. The composition of any of paragraphs 1 to 8, wherein the        linear ethylene containing polymer is a polymer of an ethylene        and at least one alpha olefin having 5 to 20 carbon atoms, where        the linear ethylene containing polymer has a melt index (190°        C./2.16 kg) of from 0.1 to 15 dg/min; a CDBI of at least 70%, a        density of from 0.910 to 0.930 g/cm³; a haze value of less than        20; a melt index ratio of from 35 to 80; an averaged modulus (M)        of from 20 000 to 60 000 psi and a relation between M and the        dart impact strength in g/mil, DIS, complying with the formula:

DIS≧0.8[100+exp(11.71−0.000268M+2.183×10⁻⁹M²)].

11. The composition of any of paragraphs 1 to 8, wherein the linearethylene containing polymer has a density of 0.940 g/cm³ or more.12. The composition of any of paragraphs 1 to 8, wherein the compositionhas one or more of:

-   -   a) a decrease in the viscoelastic phase angle (6) at a complex        modulus of 10 kPa at 190° C. (as described in the Examples        section below) of at least 0.3° per wt % of the in-reactor        polymer blend added relative to the linear ethylene containing        polymer; and/or    -   b) an increase in the degree of shear thinning at 190° C. (as        described in the Examples section below) of at least 0.002 per        wt % of the in-reactor polymer blend added relative to the        linear ethylene containing polymer; and/or    -   c) a Young's Modulus (modified ASTM D 638) of at least 250 MPa        or more (preferably 300 MPa or more, preferably 350 MPa or        more); and/or    -   d) strain at yield (modified ASTM D 638) of at least 2% or more        (preferably 4% or more, preferably 5% or more); and/or    -   e) stress at yield (modified ASTM D 638) of at least 5 MPa or        more (preferably 7 MPa or more, preferably 9 MPa or more);        and/or    -   f) stress at 100% strain (modified ASTM D 638) of at least 5 MPa        or more (preferably 7 MPa or more, preferably 10 MPa or more);        and/or    -   g) strain at break (modified ASTM D 638) of at least 150% or        more (preferably 200% or more, preferably 230% or more); and/or    -   h) stress at break (modified ASTM D 638) of at least 15 MPa or        more (preferably 20 MPa or more, preferably 22 MPa or more);        and/or    -   i) toughness (determined as described in the Examples section)        of at least 25 MJ/m³ or more (preferably 30 MJ/m³ or more,        preferably 32 MJ/m³ or more).        13. A process to produce the composition of any of the above        paragraphs 1 to 12 comprising:

1) preparing an in-reactor blend by contacting a metallocene catalystcompound and an activator with ethylene, comonomer, and a macromonomerhaving at least 50% vinyl terminal unsaturation based on the totalunsaturated olefin chain ends, where the macromonomer has an M_(w) of20,000 g/mol or more, a density of 0.920 g/cm³ or more, and optionally amelting point of 110° C. or more;

2) obtaining an in-reactor blend comprising:

-   -   (a) a first ethylene polymer comprising 90 wt % to 100 wt %        ethylene and from 0 wt % to less than 10 wt % comonomer, said        first ethylene polymer component having density of greater than        0.920 g/cm³ and an M_(w) of 20,000 g/mol or more;    -   (b) a second ethylene polymer comprising from 70 wt % to 90 wt %        ethylene and 30 wt % to 10 wt % comonomer, said second ethylene        polymer having a density of 0.910 g/cm³ or less;        wherein the in-reactor polymer blend has:    -   (a) at least 78 wt % ethylene;    -   (b) a T_(m) of at least 100° C. over a density ranging from 0.84        to 0.92 g/cm³;    -   (c) an elongation at break of 300% or more;    -   (d) a strain hardening ratio, M300/M100, of at least 1.2;    -   (e) a ratio of complex viscosity at 0.01 rad/s to the complex        viscosity at 100 rad/s of at least 30; and    -   (f) a shear thinning index of less than −0.2;

3) combining at least 1 wt % of the in-reactor blend with a linearethylene containing polymer having a density of at least 0.910 g/cm³.

14. The process of paragraph 13, wherein the process to produce thein-reactor blend occurs in the solution phase, gas phase or slurryphase.15. The process of paragraph 13 or 14, wherein the macromonomer is madein the same reactor as the in-reactor blend.16. The process of paragraph 13, 14, or 15, where the process to producethe in-reactor blend comprises:

-   -   (i) contacting at least one first monomer composition comprising        ethylene with a first catalyst capable of producing ethylene        polymer having a density of 0.920 g/cm³ or more and an M_(w) of        20,000 g/mol or more at the selected polymerization conditions        in a first polymerization stage under conditions including a        first temperature sufficient to produce the ethylene-containing        first polymer comprising at least 50% vinyl chain ends; and    -   (ii) contacting at least part of said first polymer with a        second monomer composition comprising ethylene and comonomer and        with a second catalyst capable of producing polymer having a        density of 0.910 g/cm³ or less or more in a second        polymerization stage under conditions including a second        temperature sufficient to polymerize said second monomer        composition to produce the ethylene-containing second polymer.        17. The process of paragraph 16, wherein said first temperature        is between about 80° C. and about 140° C.; and/or wherein the        contacting (i) is conducted by slurry polymerization and/or the        contacting (ii) is conducted by solution polymerization; and/or        wherein each of the contacting (i) and contacting (ii) is        conducted in the presence of a single site catalyst comprising        at least one metallocene catalyst and at least one activator.

The invention will now be more particularly described with reference tothe accompanying non-limiting Examples.

EXPERIMENTAL SECTION

Peak melting point, T_(m), (also referred to as melting point), peakcrystallization temperature, T_(c), (also referred to as crystallizationtemperature), glass transition temperature (T_(g)), heat of fusion(ΔH_(f) or H_(f)), and percent crystallinity were determined using thefollowing DSC procedure according to ASTM D3418-03. Differentialscanning calorimetric (DSC) data were obtained using a TA Instrumentsmodel Q100 machine. Samples weighing approximately 5-10 mg were sealedin an aluminum hermetic sample pan. The DSC data were recorded by firstgradually heating the sample to 200° C. at a rate of 10° C./minute. Thesample was kept at 200° C. for 2 minutes, cooled to −90° C. at a rate of10° C./minute, followed by an isothermal for 2 minutes and heating to200° C. at 10° C./minute. Both the first and second cycle thermal eventswere recorded. Areas under the endothermic peaks were measured and usedto determine the heat of fusion and the percent of crystallinity. Thepercent crystallinity is calculated using the formula, [area under themelting peak (J/g)/B(J/g)]*100, where B is the heat of fusion for the100% crystalline homopolymer of the major monomer component. Thesevalues for B are to be obtained from the Polymer Handbook, FourthEdition, published by John Wiley and Sons, New York 1999, providedhowever that a value of 189 J/g (B) is used as the heat of fusion for100% crystalline polypropylene, a value of 290 J/g is used for the heatof fusion for 100% crystalline polyethylene. The melting andcrystallization temperatures reported here were obtained during thesecond heating/cooling cycle.

For polymers displaying multiple endothermic and exothermic peaks, allthe peak crystallization temperatures and peak melting temperatures werereported. The heat of fusion for each endothermic peak was calculatedindividually. The percent crystallinity is calculated using the sum ofheat of fusions from all endothermic peaks. Some of polymer blendsproduced show a secondary melting/cooling peak overlapping with theprincipal peak, which peaks are considered together as a singlemelting/cooling peak. The highest of these peaks is considered the peakmelting temperature/crystallization point.

Morphology data were obtained using an Atomic Force Microscope (AFM) intapping phase. All specimens were analyzed within 8 hours aftercryofacing to prevent specimen relaxation. During cryofacing, thespecimens were cooled to −130° C. and cut with diamond knives in aReichert cryogenic microtome. They were then stored in a dissector underflowing dry nitrogen gas to warm up to ambient temperatures withoutcondensation being formed. Finally, the faced specimens were mounted ina miniature steel vise for AFM analysis. The AFM measurements wereperformed in air on a NanoScope Dimension 3000 scanning probe microscope(Digital Instrument) using a rectangular 225-mm Si cantilever. Thestiffness of the cantilever was ˜4 N/m with a resonance frequency of ˜70kHz. The free vibration amplitude was high, in the range of 80 nm to 100nm, with a RMS setting of 3.8 volts. While the set point ratio wasmaintained at a value equal to or lower than 0.5, the contact set pointwas adjusted routinely to ensure repulsive contacts with positive phaseshifts. The cantilever was running at or slightly below its resonancefrequency.

Comonomer content such as butene, hexene and octene was determined viaFTIR measurements according to ASTM D3900 (calibrated versus ¹³C NMR). Athin homogeneous film of polymer, pressed at a temperature of about 150°C., was mounted on a Perkin Elmer Spectrum 2000 infraredspectrophotometer. The weight percent of copolymer is determined viameasurement of the methyl deformation band at 1375 cm⁻¹. The peak heightof this band is normalized by the combination and overtone band at 4321cm⁻¹, which corrects for path length differences.

Molecular weights (number average molecular weight (M_(n)), weightaverage molecular weight (M_(w)), and z-average molecular weight(M_(z))) were determined using a Polymer Laboratories Model 220 hightemperature SEC with on-line differential refractive index (DRI), lightscattering, and viscometer detectors. It used three Polymer LaboratoriesPLgel 10 m Mixed-B columns for separation using a flow rate of 0.54ml/min and a nominal injection volume of 300 μL. The detectors andcolumns are contained in an oven maintained at 135° C. The lightscattering detector is a high temperature miniDAWN (Wyatt Technology,Inc.). The primary components are an optical flow cell, a 30 mW, 690 nmlaser diode light source, and an array of three photodiodes placed atcollection angles of 45°, 90°, and 135°. The stream emerging from theSEC columns is directed into the miniDAWN optical flow cell and theninto the DRI detector. The DRI detector is an integral part of thePolymer Laboratories SEC. The viscometer is a high temperatureviscometer purchased from Viscotek Corporation and comprising fourcapillaries arranged in a Wheatstone bridge configuration with twopressure transducers. One transducer measures the total pressure dropacross the detector, and the other, positioned between the two sides ofthe bridge, measures a differential pressure. The viscometer is insidethe SEC oven, positioned after the DRI detector. The details of thesedetectors as well as their calibrations have been described by, forexample, T. Sun, P. Brant, R. R. Chance, and W. W. Graessley, inMacromolecules, Volume 34, Number 19, pp. 6812-6820, (2001),incorporated herein by reference.

Solvent for the SEC experiment was prepared by adding 6 grams ofbutylated hydroxy toluene (BHT) as an antioxidant to a 4 liter bottle of1,2,4 trichlorobenzene (TCB) (Aldrich Reagent grade) and waiting for theBHT to solubilize. The TCB mixture was then filtered through a 0.7micron glass pre-filter and subsequently through a 0.1 micron Teflonfilter. There was an additional online 0.7 micron glass pre-filter/0.22micron Teflon filter assembly between the high pressure pump and SECcolumns. The TCB was then degassed with an online degasser (Phenomenex,Model DG-4000) before entering the SEC. Polymer solutions were preparedby placing dry polymer in a glass container, adding the desired amountof TCB, then heating the mixture at 160° C. with continuous agitationfor about 2 hours. All quantities were measured gravimetrically. The TCBdensities used to express the polymer concentration in mass/volume unitswere 1.463 g/ml at room temperature and 1.324 g/ml at 135° C. Theinjection concentration ranged from 1.0 to 2.0 mg/ml, with lowerconcentrations being used for higher molecular weight samples.

Temperature rising elution fractionation (TREF) analysis is conductedusing Polymer Char TREF 200 (PolymerChar, Valencia, Spain) equipped withan infrared detector according to the method described by Wilde, L.;Ryle, T. R.; Knobeloch, D. C.; Peat, I. R.; Determination of BranchingDistributions in Polyethylene and Ethylene Copolymers, J. Polym. Sci.,20, pp. 441-455 (1982). The polymer samples is first dissolved in 1,2dichlorobenzene with 400 ppm of butylated hydroxy toluene (BHT) at 160°C. for about 60 minutes at a polymer concentration of 2 to 6 mg/ml. Theresulting solution is then introduced into a packed column andstabilized at 140° C. for about 45 minutes. The polymer sample is thenallowed to crystallize in the packed column by slowly reducing thetemperature to 30° C. or 0° C. at a cooling rate of 1° C./min. Thesample is then first eluted from the column by pumping the solventthrough the column at a flow rate of 1.0 ml/min for 10 minutes at 0° C.or 30° C. A TREF chromatogram curve is then generated by eluting thecrystallized polymer sample from the column by slowly increasing thetemperature of the eluting solvent from 0° C. or 30° C. to 140° C. at arate of 2° C./min and eluting solvent flow rate of 1.0 ml/min. Theconcentration of eluted polymer is measured using the infrared detector.

Crystallization analysis fractionation (CRYSTAF) was conducted using aCRYSTAF 200 unit commercially available from PolymerChar, Valencia,Spain. The sample is dissolved in 1,2 dichlorobenzene at 160° C. at apolymer concentration of about 0.2 to 1.0 mg/ml for about 1 hour andstabilized at 95° C. for about 45 minutes. The sampling temperaturesrange from 95° C. to 30° C. or 95° C. to 0° C. at a cooling rate of 0.2°C./min. An infrared detector is used to measure the polymer solutionconcentrations. The cumulative soluble concentration is measured as thepolymer crystallizes while the temperature is decreased. The analyticalderivative of the cumulative profile reflects the crystallinitydistribution of each polymer components of the in-reactor polymerblends. The CRYSTAF peak temperature and area are identified by the peakanalysis module included in the CRYSTAF Software. The CRYSTAF peakfinding routine identifies a peak temperature as a maximum in the dW/dTcurve and the area between the largest positive inflections on eitherside of the identified peak in the derivative curve.

Shore hardness was determined according to ASTM D2240.

Stress-strain properties, including ultimate tensile strength, ultimateelongation, Young's modulus, and 100% modulus, of the in-reactor polymerblends were determined at room temperature according to ASTM D638 at 23°C. Tensile properties were measured on an Instron™ model 4502 equippedwith a 22.48 lb load cell and pneumatic jaws fitted with serrated gripfaces. Deformation was performed at a constant crosshead speed of 5.0in/min with a data sampling rate of 25 points/second. Initial modulus,stress and strain at yield (where evident), peak stress, tensilestrength at break, and strain at break were calculated. A minimum offive specimens from each plaque was tested, the results being reportedas the average value. All stresses quoted were calculated based upon theoriginal cross-sectional area of the specimen, taking no account ofreduced cross-section as a function of increasing strain. Tensilestrength is defined as the maximum tensile stress. Tensile toughness isdefined as the ability of polymer to absorb applied energy. The areaunder the stress-strain curve is used as a measure of the toughness. FormLLDPE's and their blends with the in-reactor polymer blend, a modifiedASTM D638 method was used, e.g., the molded plaques with a thickness ofabout 2 mm obtained from a press at 180° C., a molding time of 15 min,and a force of 25 tons was die-cut into micro-dumbbell specimens (thebase was ˜1 cm×1 cm and the center, narrow strip was ˜0.6 cm×0.2 cm).Stress-strain measurements under tension were performed in a MTS® ReNew™4502 (Upgrade Package) tensile tester. Measurements using triplicatesamples (conditioned under ambient conditions for 24 hr prior to tests)were performed at room temperature and at a separation speed of 2.0in/min. The stress was calculated based on the undeformedcross-sectional area of the test specimen. Strain measurements werebased on clamp separation. The tensile toughness was calculated as thetotal area under the stress-strain curve.

Melt index (MI) was determined according to ASTM D1238 using a load of2.16 kg at a temperature of 190° C.

Density is determined according to ASTM D1505 using a density-gradientcolumn, as described in ASTM D1505, on a compression-molded specimenthat has been slowly cooled to room temperature (i.e., over a period of10 minutes or more) and allowed to age for a sufficient time that thedensity is constant within +/−0.001 g/cm³.

Dynamic Mechanical Thermal Analysis (DMTA) examines the behavior ofviscoelastic materials according to temperature and frequency dependentbehavior. The application of a small stress produces a deformation(strain) in the material. The amount of deformation resulting from theapplied stress yields information concerning the moduli of the material;its stiffness and damping properties. The DMTA is a controlled stressinstrument applied in a sinusoidal fashion and gives a sinusoidalresponse versus time. As a consequence of the applied sinusoidal stressthe material responds in an elastic (stores energy) and viscous(dissipates energy) manners. DMTA separates these responses into twodifferent moduli values: Elastic Modulus (E′) and the loss modulus (E″)and in a temperature sweep these moduli is measured from the glassyregion, the plateau region to the terminal region. The response ofviscoelastic materials is out of phase with the input signal by an angledelta (δ). The tangent of this angle is equal to the ratio E″/E′ and itis a valuable indicator of the relative damping ability of the material.Any peak in the tan δ corresponds to a region where the materialproperties are changing very rapidly; the material is undergoing atransition or relaxation such as T_(g) (glass transition temperature)and other relaxations. For purpose of this invention and the claimsthereto, T_(g) is determined by DSC, unless DSC cannot determine aT_(g), then DMTA shall be used. In the DMTA measurements, the instrumentused was the DMTA V in tension mode (0.05% strain, 1 Hz frequency, 2°C./min heating rate, and a temperature range of ca. −100° C. to 150°C.). Compression-molded samples obtained from a press at 180° C., amolding time of 15 min, and a force of 25 tons, had dimensions of ˜23mm×6.42 mm×0.7 mm and were conditioned under ambient conditions for 24hr before the measurements.

Dynamic shear melt rheological data was measured with an AdvancedRheometrics Expansion System (ARES) using parallel plates (diameter=25mm) at several temperatures (150° C., 170° C., 190° C., and 210° C.)using a pristine compression molded sample at each temperature. Themeasurements were made over the angular frequency ranged from 0.01-100rad/s. Depending on the molecular weight and temperature, strains of 10%and 15% were used and linearity of the response was verified. A nitrogenstream was circulated through the sample oven to minimize chainextension or cross-linking during the experiments. All the in-reactorpolymer blend samples were compression molded at 190° C. and nostabilizers were added. A sinusoidal shear strain is applied to thematerial if the strain amplitude is sufficiently small that materialbehaves linearly. It can be shown that the resulting steady-state stresswill also oscillate sinusoidally at the same frequency but will beshifted by a phase angle δ with respect to the strain wave. The stressleads the strain by δ. For purely elastic materials δ=0° (stress is inphase with strain) and for purely viscous materials, δ=90° (stress leadsthe strain by 90° although the stress is in phase with the strain rate).For viscoelastic materials 0<δ<90°. The shear thinning slope (STS) wasmeasured using plots of the logarithm (base ten) of the dynamicviscosity versus logarithm (base ten) of the frequency. The slope is thedifference in the log(dynamic viscosity) at a frequency of 100 rad/s andthe log(dynamic viscosity) at a frequency of 0.01 rad/s divided by 4.For mLLDPE's and their blends with the in-reactor polymer blend, themolded plaques with a thickness of about 2 mm obtained from a press at180° C., a molding time of 15 min, and a force of 25 tons was die-cutinto 25-mm diameter circular specimens. The polymer or blend rheologywas measured by a Rheometric Scientific™ ARES Analyzer (1998) equippedwith the 25-mm diameter parallel plates. The strain used was 10% at 190°C. The frequency was varied from 0.01 to 100 rad/s.

Examples 1 to 5

These examples demonstrate the use of a mixed catalyst polymerization ina single reactor operated in a continuous stirred-tank solution process.The catalysts employed were a biscyclopentadienyl zirconium dimethyl(Catalyst A) to produce higher density polyethylene and1,1′-bis(4-triethylsilylphenyl)-methylene-(cyclopentadienyl)(2,7-ditert-butyl9-fluorenyl)hafnium dimethyl catalyst (Catalyst B) to produce lower densityethylene/hexene copolymer in the same reactor. The reactor was 1.0-literstainless steel autoclave reactor equipped with a stirrer, awater-cooling/steam-heating element with a temperature controller, and apressure controller. Solvents, monomers such as ethylene and hexene werefirst purified by passing through a three-column purification system.Purification columns were regenerated periodically whenever there wasevidence of lower activity of polymerization.

Catalyst A was preactivated with N,N-dimethylaniliniumtetrakis(heptafluoro-2-naphthyl)borate (Activator A) at a molar ratio ofabout 1:1 in 900 ml of toluene. Catalyst B was preactivated withN,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (Activator B) ata molar ratio of about 1:1 in 900 ml of toluene. All catalyst solutionswere kept in an inert atmosphere with <1.5 ppm water content and fedinto reactors by metering pumps. Tri-n-octylaluminum (TNOA) solution wasused as a scavenger. Scavenger feed rate was adjusted and optimized toachieve good yield at beginning of each run.

The solvent feed to the reactor was measured by a mass-flow meter. APulsa feed pump controlled the solvent flow rate and increased thesolvent pressure to the reactor. The compressed, liquefied hexene feedwas measured by a mass flow meter and the flow was controlled by a Pulsafeed pump. The solvent, monomers were fed into a manifold first.Ethylene from in-house supply was delivered in the chilledsolvent/monomer mixture in the manifold. The mixture of solvent andmonomers were then chilled to about −15° C. by passing through a chillerprior to feeding into the reactor through a single tube. Ethylene flowrate was metered through a Brookfield mass flow controller.

The reactor was first cleaned by continuously pumping solvent (e.g.,isohexane) and scavenger through the reactor system for at least onehour at a maximum allowed temperature (about 150° C.). After cleaning,the reactor was heated/cooled to the desired temperature usingwater/steam mixture flowing through the reactor jacket and controlled ata set pressure with controlled solvent flow. Monomers and catalystsolutions were then fed into the reactor. An automatic temperaturecontrol system was used to control and to maintain the reactors at settemperatures. Onset of polymerization activity was determined byobservations of a viscous product and lower temperature of water-steammixture. Once the activity was established and system reached steadystate, the reactor was lined out by continuing operating the systemunder the established condition for a time period of at least five timesof mean residence time prior to sample collection. The resulting mixturefrom the reactor, containing mostly solvent, polymer and unreactedmonomers, was collected in a collection box. The collected samples werefirst air-dried in a hood to evaporate most of the solvent, and thendried in a vacuum oven at a temperature of about 90° C. for about 12hours. The vacuum oven dried samples were weighed to obtain yields. Allthe reactions were carried out at a pressure of about 2.4 MPa-g. Thedetailed reaction conditions and polymer properties are listed in Table1, where the molecular weight data were based on the light scattering(LS) results.

TABLE 1 Example # 1 2 3 4 5 Polymerization temperature (° C.) 90 90 8080 80 Ethylene feed rate (SLPM*) 4 4 4 4 4 Hexene feed rate (ml/min) 1010 10 10 10 Catalyst A feed rate (mol/min) 1.41E−07 1.41E−07 1.41E−071.41E−07 8.84E−08 Catalyst B feed rate (mol/min) 3.53E−07 2.36E−073.53E−07 2.36E−07 3.53E−07 Polymer yield (g/min) 4.7 4.9 4.7 4.9 5.7Conversion (%) 41.4 43.3 41.9 43.7 51 I2 (2.16 kg, 190° C.) (dg/min)22.76 38.13 2.08 1.21 <0.1 I21 (21.6 kg, 190° C.) (dg/min) 434.24 781.651.41 44.68 4.05 M_(n) (kg/mol) 28.46 22.32 48.79 51.84 90.66 M_(w)(kg/mol) 90.83 62.60 185.86 315.12 798.65 M_(z) (kg/mol) 484.02 317.39896.48 1191.81 1757.55 T_(c) (° C.) 86.1 81.8 84.3 86.7 95.3 T_(m) (°C.) 106.2 101.9 106.1 108.0 115.0 T_(g) (° C.) −63.0 Heat of fusion(J/g) 112.8 104.5 92.8 87.5 46.6 T_(c) from a secondary peak (° C.) 54.048.8 56.4 58.6 63.5 Density (g/cm³) 0.9063 0.9070 0.9033 0.8978 0.8768FTIR ethylene (wt %) 82.15 83.35 83.77 77.05 63.17 ¹³C NMR ethylene (wt%) 82.41 76.51 61.01 Critical Relaxation Exponent, n 0.41 0.25 0.22Shear Thinning Index (STS) −0.360 −0.559 −0.742 Stress @ yield (MPa)7.19 7.05 7.36 Tensile strength (MPa) 15.69 18.23 26.32 20.80 6.15Stress @ 100% strain (MPa) 7.10 6.88 7.27 6.17 2.45 Stress @ 300% strain(MPa) 8.34 8.13 9.66 8.26 3.24 Stress @ 500% strain (MPa) 11.6 11.5015.22 13.39 4.20 Stress @ 700% strain (MPa) 15.80 23.12 19.33 5.27Strain @ break (%) 694.98 817.00 830.00 748.89 1051.22 Toughness (MJ/m³)67.89 84.47 106.17 81.92 45.81 *Standard Liter Per Minute

The complex viscosity of the in-reactor polymer blends produced inExamples 3 to 5 was measured at temperature 190° C. over a frequencyranging from 0.01 to 100 rad/s. Significant shear thinning was observed.The ratio of complex viscosity at a frequency of 0.01 rad/s to thecomplex viscosity at a frequency of 100 rad/s is 27.5, 171.5 and 926.6for materials produced in Example 3, 4, and 5, respectively. The complexviscosity profiles are shown in FIG. 1. The present in-reactor blendsexhibit a number of important properties. Examples 3-5 have a shearthinning index (e.g., shear thinning slope (see STS in Table 1)), theslope of the log (complex viscosity) versus log (frequency) curve, of−0.360, −0.559, and −0.742, respectively. The more negative this slope,the faster the dynamic viscosity decreases as the frequency increases.These types of polymer blends are easily processed in high shear ratefabrication methods, such as injection molding. Large negative shearthinning slopes occur when blends are highly branched.

When the loss or phase angle is plotted versus frequency for Examples 3to 5, the loss angles are nearly independent of frequency and a plateauis observed. This is gel-like behavior and the critical relaxationexponent can be calculated as the ratio of the loss angle of the plateaudivided by 90°. The critical relaxation exponents for Examples 3 to 5are less than or equal to 0.41. Linear polyolefins do not have plateausin their plots of loss angle versus frequency. According toGarcia-Franco, et al., Macromolecules 34(10), 2001, pp. 3115-3117, thelower the critical relaxation exponent, the more extensive the longchain branches in the sample. The critical relaxation exponents observedfor the blends of this invention are lower than any reported in thispaper. Based upon a comparison with Garcia-Franco's data, Examples 3 to5 have more than one branch per 10000 carbons.

The loss angle is the inverse tangent of the storage modulus divided bythe loss modulus. For linear polymer chains the polymer melt is fullyrelaxed at small frequencies or long relaxation times; the storagemodulus is much larger than the loss modulus and the loss angles are90°. For the in-reactor blends of Examples 3 to 5 the loss modulus isstill larger than the storage modulus even at a frequency of 0.01 rad/s.The chains are unable to relax, because of the presence of significantamounts of branching between the higher density polyethylene and lowerdensity ethylene copolymer chains. These effects must be due tobranching, because the experiment was carried out at a temperature of190° C., above the melting points of both polymers in the blend.

In FIG. 2 the loss angle data collected at 140° C., 150° C., 170° C.,190° C., and 210° C. are plotted versus the dynamic shear modulus, G*,for Examples 3, 4, and 5. These plots are known as van Gurp/Palmenplots. According to Garcia-Franco, et al., European Polymer Journal 44(2008), pp. 376-391, these plots collected at different temperaturesshould superimpose for linear polyolefins as a result of the well knowntime-temperature superposition principle. It can be seen that the plotsfor Examples 3 to 5 do not superimpose, because these in-reactor polymerblends are highly branched. According to this paper the lower the valuesof the loss or phase angle, the greater the level of long chainbranches.

The dynamic viscosity at low shear rates is highly sensitive to thosechains in the melt which relax slowly. To quantify how many chains withlong relaxation times are present in the melt, the dynamic moduli, G′and G″, measured at 190° C. were fit with a Generalized Maxwell model.Using the amount of the chains with 100 second relaxation times dividedby the zero shear viscosity, viscosity fractions of 0.83, 0.90, and 0.89were calculated for the chains with 100 second relaxation times for thein-reactor blends of Examples 3, 4, and 5. These slowly relaxing chainslead to high zero shear viscosities and shear thinning as demonstratedin FIG. 1. Long relaxation times also lead to high melt strengths andeasy processing in extruders.

¹³C NMR spectra were collected for Examples 3 to 5. The peaks wereassigned and analyzed using the method of M. R. Seger and G. E. Maciel,Anal. Chem. 2004, 76, pp. 5734-5747. The ethylene weight percent forthese Examples is presented in Table 1. A peak for the methine in themiddle of a HHH pentad was present at 33.7 ppm. This is where themethine at the branch points of the cross products would also be seen,so the amount of cross products could not be quantified for theseExamples.

The in-reactor blends produced in the Examples 1 to 5 were compressedinto plaques for the tensile testing according to the proceduredescribed above. The strain-stress properties of the products are listedin Table 1. Five replicas are averaged for the results. Thestrain-stress curves for Examples 3 to 5 are shown in FIG. 3. Strainhardening is observed after the yield point for all examples. Strainhardening index is the increase of stress in the stress-strain curvesafter yielding. For polymer in Example 3, M300/M100=1.3, M500/M100=2.1,and M700/M100=3.2. It is believed that strain hardening is observedbecause parts of the chains in the reactor blend are immobilized incrystallites or by branch points. The in-reactor blend of Example 4behaves as a crosslinked elastomer or a thermoplastic elastomer.

The data obtained from DSC for material in Example 1 to 5 are listed inTable 1. All of the polymer blends have high peak melting temperatures,and the peak melting temperatures are significant higher than those ofrandom ethylene copolymers with similar density. For the materialproduced in Example 5, T_(m)=115° C. with a density of 0.8768 g/cm³. Forall of these samples, there is a shoulder connected to the primarycrystallization peak. The peak temperatures for these shoulders arearound 48° C. to 64° C.

Materials produced in Examples 3 to 5 have a faction eluted between 50°C. to 90° C. and a soluble fraction which elutes below 0° C. whenfractionated using TREF according to the procedure described above. Thefraction corresponding to the highest temperature peak is referred to asthe high-crystalline fraction. The soluble fraction is thereforereferred to as amorphous elastomeric component. The peak temperaturesfor each fraction will be varied depending on the density of eachcomponent. TREF traces of dW/dT vs. elution temperature T for materialproduced in Examples 3 to 5 are shown in FIG. 4.

Polymer produced in Example 4 was also subjected to fractionation usinga preparative temperature elution fractionation. Four fractions werecollected at temperatures of 30° C., 45° C., 55° C., and 90° C. Theweight percent for each fraction is listed in Table 2. Some of theanalytical data for each fraction is also included in Table 2. The largefraction located below 30° C. is attributed to low density-component,while the large fraction above 90° C. is attributed to high densitypolyethylene component. Each fraction was also subjected tofractionation using a CRYSTAF in a temperature range from roomtemperature to 100° C. The CRYSTAF spectra for these four fractions andfor the whole sample of Example 4 are plotted in FIG. 5 and are labeledas FR#1 to FR#4. DSC analysis revealed that all of these fractions havea similar T_(m) ranging from 106° C. to 109° C. and a similar T_(c)ranging from 88° C. to 91° C. It was surprised to observe that fraction#1 has a peak melting temperature of 107.8° C. and a heat of fusion of58.6 J/g. Moreover, the molecular weight distribution for all fourfractions showed a bi-modal distribution. In other word, this polymerblend cannot have a clean separation of lower density component and ahigher density polyethylene component. Every fraction seems to containat least two different components of polymer. It is believed that thismulti-characteristic feature of each fraction is due to the present ofbranched block structure in the polymer blend.

TABLE 2 FR#1 FR#2 FR#3 FR#4 Cut off temperature (° C.) 30 45 55 90Weight percent of each 39.2 3.7 4.4 52.7 fraction M_(n) (kg/mol) 73.4327.50 26.73 45.45 M_(w) (kg/mol) 433.73 117.68 85.87 116.95 M_(z)(kg/mol) 1179.06 620.69 448.80 536.2 Molecular weight bi- bi- bi- bi-distribution modal modal modal modal T_(c) (° C.) 88.0 90.3 91.0 89.1T_(m) (° C.) 107.8 108.1 106.6 108.3 Heat of fusion (J/g) 58.6 111.2111.6 106.8 First peak temperature in 57.1 58.1 57.8 58.5 CRYSTAF (° C.)Fraction of the first peak 37.9 71.3 47.5 97.3 in CRYSTAF (%) Secondpeak temperature 40.9 49.4 in CRYSTAF (° C.) Fraction of the 2nd peak18.3 35.5 in CRYSTAF (%) Soluble fraction in 58 8.7 2.4 CRYSTAF (<30°C.) (%)

The morphology of each of the blends produced in Examples 3 and 5 wasexamined using AFM according to the procedure described above and theresults are shown in FIG. 6. A heterogeneous morphology was observed formaterials produced in the Examples 3 and 5. For example 3, the highdensity component is the matrix phase and the low density is in discreteparticle phase. The low density and high density components are in aco-continuous morphology for the polymer blend in Example 5.

Examples 6 to 9

Examples 6 to 9 were made by following the same procedure used inExamples 1 to 5 except that different types of catalysts were used inExamples 7 and 8. In Example 7, 2,6-diacetylpyridinebis(2,4,6-trimethylphenylimine) iron dichloride (Catalyst C) was used toproduce higher density polyethylene and Catalyst B was used for thelower density ethylene/hexene copolymer. 100 mg of 2,6-diacetylpyridinebis(2,4,6-trimethylphenylimine) iron dichloride was first mixed with 8ml of tri-n-octyl aluminum solution (25 wt %) in 900 ml of toluene forat least 10 minutes, then 160 mg of Activator B was added into thesolution to form a catalyst solution. In Example 8, pentamethylcyclopentadienyl 1,3 dimethyl indenyl hafnium dimethyl (Catalyst D) wasused to make higher density polyethylene and Catalyst B was used toproduce the lower density ethylene/hexene copolymer. Pentamethylcyclopentadienyl 1,3 dimethyl indenyl hafnium dimethyl was preactivatedwith Activator B at a molar ratio of about 1:1 in 900 ml of toluene. Thedetailed process conditions and some property data are listed in Table3. Example 9 was made using only catalyst B, and is a comparativeexample.

TABLE 3 Example # 6 7 8 9 Polymerization temperature (° C.) 85 100 80 85Ethylene feed rate (SLPM*) 4 6 4 4 Hexene feed rate (ml/min) 4 7 10 6Catalyst for higher density PE Catalyst A Catalyst C Catalyst D —Catalyst A feed rate (mol/min) 5.3E−08 2.119E−07 1.323E−07 0 Catalystfor lower density Catalyst B Catalyst B Catalyst B Catalyst Bethylene/hexene copolymer Catalyst B feed rate (mol/min) 7.06E−081.766E−07 7.888E−08 6.71E−08 Polymer yield (g/min) 3.3 3.8 3.6 6.2Conversion (%) 45.7 33 32.3 72.6 I2 (2.16 kg, 190° C.) (dg/min) <0.1<0.1 <0.1 M_(n) (kg/mol) 153.3 88.3 155.7 426.7 M_(w) (kg/mol) 1229.9395.9 506.4 1070.3 M_(z) (kg/mol) 2659.5 1192.5 1153.1 2104.1 T_(c) (°C.) 103.5 105.4 103.7 19.2 T_(m) (° C.) 123.6 114.9 123.9 45.5 T_(g) (°C.) −44.4 −62.0 −53.5 Heat of fusion (J/g) 39.9 102.8 78.8 38.9 T_(c)from a secondary peak (° C.) 41.5 47.6 72.0 T_(m) from a secondary peak(° C.) 61.3 64.7 Heat of fusion from a secondary peak (J/g) 27.9 FTIRethylene content (wt %) 84.1 88.1 77.0 72.2 Stress @ yield (MPa) 10.25.7 Tensile strength (MPa) 23.6 34.4 15.2 11.8 Stress @ 100% strain(MPa) 7.5 10.5 5.9 2.4 Strain @ break (%) 514.2 641.6 713.0 560.6Toughness (MJ/m³) 62 125 65 29 *Standard Liter Per Minute

Tensile property and thermal property of the in-reactor blends producedin Examples 6 to 9 were measured using the procedures described earlyand some of results are listed in Table 3. The polymer in Example 9 wasprepared with a single metallocene catalyst, and is, more or less, likea plastomer with 27.8 wt % hexene. It shows a single T_(g) and a singleT_(m). The polymers in Examples 6 and 8 should have two amorphous phases(one associated with the amorphous ethylene/hexene (EH) phase and theother associated with the amorphous PE phase) and two crystallizedphases (one associated with the crystallized EH phase and the otherassociated with the crystallized PE phase). However, polymer in Example8 only shows one crystallized phase (associated with the crystallized PEphase) because higher amount of hexene was incorporated in the lowerdensity ethylene/hexene segments of this copolymer, resulting in aamorphous phase without any crystallinity. In Examples 6 and 7, thedifference in the peak melting temperatures between the first highcrystalline polymer and the second low crystalline polymer are 62.3° C.and 50.2° C., respectively. The total heat of fusion of Examples 6 to 9is 67.8, 102.8, 78.8, and 38.9 J/g, respectively. All the above resultsare consistent with the tensile properties of these copolymers listed inTable 3. FIG. 7 shows the full stress-strain curves of all thesepolymers. As expected, all in-reactor polymer blends (Examples 6 to 8)have better tensile properties than the comparative example, Example 9made using only Catalyst B. Also, Examples 6 and 7 have higher tensilestrengths than Example 8 because the second ethylene polymers of thesetwo former in-reactor polymer blends contain crystallinity.

Blends with LLDPE

Materials

Exceed™ Polyethylene 2018 (“Exceed PE 2018”), an mLLDPE available fromExxonMobil Chemical Company (Houston, Tex.), has an MI of 2.0 dg/min, adensity of 0.918 g/cm³, an M_(w) of 98 kg/mol, an M_(w)/M_(n) of 2.09, ahexene content of about 6.0 wt %, and a CDBI of about 82% to 85%. FromDMTA (dynamic mechanical thermal analysis) we observed that the ExceedPE 2018 has an a transition at 80° C. and a 0 transition at about −9° C.In semi-crystalline polymers such as PE's, relaxations are more complexthan amorphous polymers because they often involve coupling processes inthe crystalline and amorphous domains and individual PE's can bedominated by their peculiarities. The β transition has thecharacteristics of a T_(g), but is not observed in a linear PE,presumably because of the heavy constraints to motion imposed by thecrystalline domains in this highly crystalline linear PE material. The αtransition is even more complex, involving coupled relaxations in boththe crystalline and amorphous domains. Overall, a PE without any LCB orcomonomer will only show the α transition because its crystallinity ishigh. On the other hand, a PE with LCB and/or comonomer will show both αand β transitions when it has a lower crystallinity.

Enable™ Polyethylene 2705 (“Enable PE 2705”), a mLLDPE with long chainbranching available from ExxonMobil Chemical Company (Houston, Tex.),has an MI of 0.5 dg/min, a density of 0.927 g/cm³, an M_(w) of 109kg/mol, an M_(w)/M_(n) of 2.87, a hexene content of about 4.5 wt %, andan CDBI of about 85%. It is an essentially linear ethylene containingpolymer with about 1 wt % long chain branching. From DMTA, we observedthat the Enable PE 2705 has an α transition at 88° C. but no βtransition. It is likely that no beta transition was detected becauseEnable PE 2705 has a higher density or a lower amount of comonomercompared to Exceed PE 2018.

Example 10

The in-reactor blends produced in Examples 6 to 8 along with thecomparative example of Example 9 and the commercial processabilityimprover of LD-PE 200.48 were tested as a modifier (at a concentrationof 10 wt %) for Exceed PE 2018E. The blends were prepared using aBrabender mixer (50-g capacity) at a mixing temperature of 200° C. Themixture of Exceed PE 2018 and the in-reactor blend was introduced in thepreheated Brabender mixer together with 500 ppm of Irganox 1076available from Ciba Specialty Chemicals Corporation, Tarrytown, N.Y.,1000 ppm of Irgafos 168 also available from Ciba Specialty ChemicalsCorporation, Tarrytown, N.Y., and 800 ppm of Dynamar FX 5920A availablefrom Dyneon LLC, Oakdale, Minn. A rotor speed of 50 rpm was usedthroughout the run and the system was kept at the temperature desiredand stable. Mixing was continued for 10 min once all the blendcomponents were incorporated in the Exceed PE 2018. Finally the blendwas discharged from the mixer and allowed to cool down. Polyethylene LD™200.48 (“PE-LD 200.48”) is an LDPE available from ExxonMobil ChemicalCompany (Houston, Tex.) having an MI of 7.5 dg/min and a density of0.915 g/cm³.

Table 4 reports the blend properties compared to the neat Exceed PE 2018polymer properties.

TABLE 4 Properties of Exceed PE 2018 Blended with 10 wt % of VariousIn-reactor Blends Polymer blend: 90 wt % of Exceed 2018 + 10 wt % ofmodifier Exceed PE 2018 + Exceed PE Exceed PE Exceed PE Exceed PE 10 wt% 2018 + 10 wt % 2018 + 10 wt % 2018 + 10 wt % 2018 + 10 wt % Exceed LDpolymer in polymer in polymer in polymer in Polymer blend 2018 200.48Example 9 Example 6 Example 7 Example 8 Exceed 2018 100 90 90 90 90 90(wt %) Modifier LD-PE Example 9 Example 6 Example 7 Example 8 200.48LD-PE 200.48 10 10 10 10 10 or in-reactor blend (wt %) δ* 81° 75° 80°72° 74° 84° Degree of 0.57 0.71 0.69 0.82 0.78 0.58 shear thinningE_(o), MPa 348 372 331 369 410 351 Strain @ yield 22 23 24 16 20 22 (%)Stress @ yield 11 11 9.3 9.6 11 10 (MPa) Stress @ 100% 11 11 10 11 11 10strain (MPa) Strain @ break 320 320 280 270 300 320 (%) Stress @ break33 30 26 27 31 30 (MPa) Toughness 54 51 38 39 48 48 (MJ/m³) *Loss orphase angle at a complex modulus of 10 kPa, E_(o) = Young's modulus

The van Gurp-Palmen and the complex viscosity versus frequency plots at190° C. of these various polymeric materials in Table 4 are compared inFIGS. 8 and 9, respectively. G* denotes the complex modulus in FIG. 8.In Table 4, we use the loss or phase angle at a G* of 10 kPa to rankthese polymeric materials. Blends with 10 wt % of in-reactor polymerblends produced in Example 6 and 7 with two T_(m)'s lower the phaseangle of Exceed PE 2018 more than LD-PE 200.48, the commercial control,FIG. 8. The polymer produced in Example 8 and polymer produced inExample 9 with one T_(m) show smaller effects. A lower phase angle at agiven G* means a higher melt elasticity. According to Garcia-Franco, etal., European Polymer Journal 44 (2008), pp. 376-391, the lower thevalues of the loss or phase angle (δ), the greater the level of longchain branches in the polymer or in the blend. The highly branchedin-reactor polymer blend in Exceed PE 2018 can slowly relax the polymerchains. The long relaxation time will result in a high melt strength.

Ten wt % of polymers produced in Examples 6 and 7 in Exceed PE 2018 notonly improve the melt strength, they also enhance the shear thinning ofthe host Exceed PE 2018, FIG. 9. The decreases in phase angle of ExceedPE 2018 are in the amounts of 0.9° and 0.7° for every 1 wt % of polymersin Examples 6 and 7 added, respectively. The increases in the degree ofshear thinning of Exceed PE 2018 are in the amounts of 0.025 and 0.021for every 1 wt % of polymers in Examples 6 and 7 added, respectively. InTable 4, the following ratio was used:

${{degree}\mspace{14mu} {of}\mspace{14mu} {shear}\mspace{14mu} {thinning}} = \frac{{\eta^{*}\left( {0.1\mspace{14mu} {{rad}/s}} \right)} - {\eta^{*}\left( {100\mspace{14mu} {{rad}/s}} \right)}}{\eta^{*}\left( {0.1\mspace{14mu} {{rad}/s}} \right)}$

to measure the degree of shear thinning, where η*(0.1 rad/s) and η*(100rad/s) are the complex viscosities at frequencies of 0.1 and 100 rad/s,respectively, measured at 190° C. The higher this ratio, the higher isthe degree of shear thinning Again, adding a suitable in-reactor polymerblend in a mLLDPE can slowly relax the polymer chains, leading to highzero shear viscosity, shear thinning, and easy processing in extruders.

The stress-strain properties are also shown in Table 4, where E_(o)denotes the Young's modulus (obtained from the initial slope of thestress-strain curve). Some of these materials showed two yield points.The values of strain at yield and stress at yield in Table 4 were basedon the first yield point starting from the lower-strain region of thestress-strain curve. Therefore, LD-PE 200.48 and polymers in Examples6-9 affect the tensile properties of Exceed PE 2018 differently.

Exceed™ Polyethylene 1018 (“Exceed PE 1018”), an mLLDPE available fromExxonMobil Chemical Company (Houston, Tex.), has an MI of 1.0 dg/min, adensity of 0.918 g/cm³, and a T_(m) of 118° C. It is expected that thein-reactor polymer blends in Examples 6 and 7 also improve the meltstrength and shear thinning of this linear ethylene containing polymerin applications, such as blown film, cast film, sheet, pipe and fiberextrusion, and co-extrusion as well as blow molding, injection molding,and rotary molding.

Example 11

The in-reactor blends produced in Examples 6 to 8 along with thecomparative example of Example 9 were tested as a modifier (at aconcentration of 10 wt %) to Enable PE 2705. The blends were preparedusing a Brabender mixer (50-g capacity) at a mixing temperature of 200°C. The mixture of Enable PE 2705 and the modifier were introduced in thepreheated Brabender mixer together with 500 ppm of Irganox 1076, 1000ppm of Irgafos 168, and 800 ppm of Dynamar FX 5920A. A rotor speed of 50rpm was used throughout the run and the system was kept at temperaturedesired and stable. Mixing was continued for 10 min once all the blendcomponents were incorporated in the Enable PE 2705. Finally the blendwas discharged from the mixer and allowed to cool down.

As shown in Table 5, the blend properties were compared to the neatEnable 2705 polymer properties.

TABLE 5 Properties of Enable 2705 Blended with 10 wt % of VariousIn-reactor Blends Polymer blend: 90 wt % of Enable PE 2705 + 10 wt % ofmodifier Polymer blend Enable 2705 + Enable 2705 + Enable 2705 + Enable2705 + 10 wt % 10 wt % 10 wt % 10 wt % Enable polymer in polymer inpolymer in polymer in 2705 Example 9 Example 6 Example 7 Example 8Enable PE 2705 (wt %) 100 90 90 90 90 In-reactor blend Example 9 Example6 Example 7 Example 8 Δ* 56° 56° 53° 51° 58° Degree of shear 0.93 0.950.96 0.95 0.94 thinning E_(o), MPa 645 583 526 564 544 Strain @ yield(%) 5.2 6.4 6.5 5.7 5.6 Stress @ yield (MPa) 14 11 11 13 12 Stress @100% strain 12 11 12 12 11 (MPa) Strain @ break (%) 330 220 230 300 160Stress @ break (MPa) 32 20 22 30 15 Toughness (MJ/m³) 57 28 32 51 18*Loss or phase angle at a complex modulus of 10 kPa, E_(o) = Young'smodulus

FIG. 10 compares the van Gurp-Palmen plot of Enable PE 2705 to those ofEnable PE2705 containing 10 wt % of each polymer produced in Examples 6to 9. In-reactor polymer blends produced in Examples 6 and 7 decreasethe phase angle of Enable PE 2705, thereby enhancing the melt elasticityand melt strength of Enable PE 2705. The decreases in phase angle ofEnable PE 2705 are in the amounts of 0.3° and 0.5° for every 1 wt % ofpolymers in Examples 6 and 7 added, respectively. In Table 5, the lossor phase angle at G*=10 kPa is used to rank these polymeric materials.Also, in-reactor polymer blends produced in Examples 6 and 7, afterblended with Enable PE 2705, produce enhancements in the degree of shearthinning, Table 5. The increases in the degree of shear thinning ofEnable PE 2705 are in the amounts of 0.003 and 0.002 for every 1 wt % ofpolymers in Examples 6 and 7 added, respectively.

All documents described herein are incorporated by reference herein forpurposes of all jurisdictions where such practice is allowed, includingany priority documents and/or testing procedures to the extent they arenot inconsistent with this text, provided however that any prioritydocument not named in the initially filed application or filingdocuments is NOT incorporated by reference herein. As is apparent fromthe foregoing general description and the specific embodiments, whileforms of the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited thereby. Likewise, the term “comprising” is consideredsynonymous with the term “including” for purposes of Australian law.Likewise whenever a composition, an element or a group of elements ispreceded with the transitional phrase “comprising”, it is understoodthat we also contemplate the same composition or group of elements withtransitional phrases “consisting essentially of,” “consisting of”,“selected from the group of consisting of,” or “is” preceding therecitation of the composition, element, or elements and vice versa.

1. A composition comprising: 1) a linear ethylene containing polymerhaving a density of at least 0.910 g/cm³; and 2) an in-reactor polymerblend comprising: (a) a first ethylene containing polymer having adensity of greater than 0.90 g/cm³ and a M_(w) of more than 20,000 g/moland (b) a second ethylene containing polymer having a density of lessthan 0.90 g/cm³, wherein the densities of the first and second polymersdiffer by at least 1%, and wherein the in-reactor polymer blend has aT_(m) of at least 90° C. (DSC second melt), a density of less than 0.92g/cm³, and contains at least 78 wt % ethylene.
 2. The composition ofclaim 1, wherein the linear ethylene containing polymer has a CDBI of60% or more.
 3. The composition of claim 1, wherein the linear ethylenecontaining polymer is an LLDPE or an HDPE.
 4. The composition of claim1, wherein the linear ethylene containing polymer has an M_(w) of 50,000g/mol or more, a g′ of 0.95 or more and an M_(w)/M_(n) of from greaterthan 1 to 10 and comprises from 50 mole % to 100 mole % ethylene andfrom 0 mole % to 50 mole % of C₃ to C₄₀ comonomer.
 5. The composition ofclaim 1, wherein the linear ethylene containing polymer is a polymer ofan ethylene and at least one alpha olefin having 5 to 20 carbon atoms,where the linear ethylene containing polymer has a melt index (190°C./2.16 kg) of from 0.1 to 15 dg/min; a CDBI of at least 70%, a densityof from 0.910 to 0.930 g/cm³; a haze value of less than 20; a melt indexratio of from 35 to 80; an averaged modulus (M) of from 20 000 to 60 000psi and a relation between M and the dart impact strength in g/mil, DIS,complying with the formula:DIS≧0.8[100+exp(11.71−0.000268M+2.183×10⁻⁹M²)].
 6. The composition ofclaim 1, wherein the linear ethylene containing polymer has a density of0.940 g/cm³ or more.
 7. A composition comprising: 1) a linear ethylenecontaining polymer having a density of at least 0.910 g/cm³; and 2) atleast 1 wt % of an in-reactor polymer blend comprising: (a) a firstethylene polymer comprising 90 wt % to 100 wt % ethylene and from 0 wt %to less than 10 wt % comonomer, said first ethylene polymer componenthaving density of greater than 0.920 g/cm³ and an M_(w) of 20,000 g/molor more; and (b) a second ethylene polymer comprising from 70 wt % to 90wt % ethylene and 30 wt % to 10 wt % comonomer, said second ethylenepolymer having a density of 0.910 g/cm³ or less, wherein the in-reactorpolymer blend has: (a) at least 78 wt % ethylene; (b) a T_(m) of atleast 100° C. over a density ranging from 0.84 to 0.92 g/cm³; (c) anelongation at break of 300% or more; (d) a strain hardening ratio,M300/M100, of at least 1.2; (e) a ratio of complex viscosity at 0.01rad/s to the complex viscosity at 100 rad/s of at least 30; and (f) ashear thinning index of less than −0.2.
 8. The composition of claim 7,wherein the difference in density between the first ethylene polymer andthe second ethylene polymer is at least 1%.
 9. The composition of claim7, wherein the first ethylene polymer has a T_(m) of 110° C. or more.10. The composition of claim 7, wherein the in-reactor blend has adensity from 0.84 to 0.92 g/cm³ and a melting point of from 100° C. to130° C.
 11. The composition of claim 7, wherein the in-reactor blend hasa strain hardening index M500/M100 of at least 1.2.
 12. The compositionof claim 7, wherein the in-reactor blend has a heat of fusion of atleast 50 J/g.
 13. The composition of claim 7, wherein the in-reactorblend has a tensile strength of greater than 15 MPa.
 14. The compositionof claim 7, wherein the in-reactor blend has an elongation at break ofgreater than 400%.
 15. The composition of claim 7, wherein thein-reactor blend has a tensile toughness of 40 MJ/m³ or more.
 16. Thecomposition of claim 7, wherein the in-reactor blend has a melt index at190° C., under a 2.16 kg load, of 0.01 to 100 dg/min.
 17. Thecomposition of claim 7, wherein the first ethylene containing polymer ofthe in-reactor blend has 95 wt % to 100 wt % ethylene and 0 wt % to 5 wt% comonomer selected from the group consisting of propylene, butene,hexene or octene.
 18. The composition of claim 7, wherein the secondethylene containing polymer of the in-reactor blend has 70 wt % to 90 wt% ethylene and 10 wt % to 30 wt % comonomer selected from the groupconsisting of propylene, butene, hexene or octene.
 19. The compositionof claim 7, wherein the first ethylene containing polymer of thein-reactor blend has a melting point of 110° C. or more and a melt indexat 190° C., under a 2.16 kg load, of 0.01 to 800 dg/min, and the secondethylene containing polymer of the in-reactor blend has a melt index at190° C., under a 2.16 kg load of 200 dg/min or less.
 20. The compositionof claim 7, wherein the second ethylene containing polymer of thein-reactor blend has a 1% secant flexural modulus from 5 to 100 MPa. 21.The composition of claim 7, wherein the in-reactor polymer blend has acyclohexane refluxing insoluble fraction of 70 wt % or less.
 22. Thecomposition of claim 7, wherein the linear ethylene containing polymerhas a CDBI of 60% or more.
 23. The composition of claim 7, wherein thelinear ethylene containing polymer is an LLDPE or an HDPE.
 24. Thecomposition of claim 7, wherein the linear ethylene containing polymerhas an M_(w) of 50,000 g/mol or more, a g′ of 0.95 or more and anM_(w)/M_(n) of from greater than 1 to 10 and comprises from 50 mole % to100 mole % ethylene and from 0 mole % to 50 mole % of C₂ to C₄₀comonomer.
 25. The composition of claim 7, wherein the linear ethylenecontaining polymer is a polymer of an ethylene and at least one alphaolefin having 5 to 20 carbon atoms, where the linear ethylene containingpolymer has a melt index (190° C./2.16 kg) of from 0.1 to 15 dg/min; aCDBI of at least 70%, a density of from 0.910 to 0.930 g/cm³; a hazevalue of less than 20; a melt index ratio of from 35 to 80; an averagedmodulus (M) of from 20 000 to 60 000 psi and a relation between M andthe dart impact strength in g/mil, DIS, complying with the formula:DIS≧0.8[100+exp(11.71−0.000268M+2.183×10⁻⁹M²)].
 26. The composition ofclaim 7, wherein the linear ethylene containing polymer has a density of0.940 g/cm³ or more.
 27. A process to produce a blend of a linearethylene containing polymer and an in-reactor blend comprising: 1)preparing an in-reactor blend by contacting a metallocene catalystcompound and an activator with ethylene, comonomer, and a macromonomerhaving at least 50% vinyl terminal unsaturation based on the totalunsaturated olefin chain ends, where the macromonomer has an M_(w) of20,000 g/mol or more, a density of 0.920 g/cm³ or more, and optionally amelting point of 110° C. or more; 2) obtaining an in-reactor blendcomprising: (a) a first ethylene polymer comprising 90 wt % to 100 wt %ethylene and from 0 wt % to less than 10 wt % comonomer, said firstethylene polymer component having density of greater than 0.920 g/cm³and an M_(w) of 20,000 g/mol or more; and (b) a second ethylene polymercomprising from 70 wt % to 90 wt % ethylene and 30 wt % to 10 wt %comonomer, said second ethylene polymer having a density of 0.910 g/cm³or less; wherein the in-reactor polymer blend has: (a) at least 78 wt %ethylene; (b) a T_(m) of at least 100° C. over a density ranging from0.84 to 0.92 g/cm³; (c) an elongation at break of 300% or more; (d) astrain hardening ratio, M300/M100, of at least 1.2; (e) a ratio ofcomplex viscosity at 0.01 rad/s to the complex viscosity at 100 rad/s ofat least 30; and (f) a shear thinning index of less than −0.2; 3)combining at least 1 wt % of the in-reactor blend with a linear ethylenecontaining polymer having a density of at least 0.910 g/cm³.
 28. Theprocess of claim 27, wherein the process to produce the in-reactor blendoccurs in the solution phase.
 29. The process of claim 27, wherein theprocess to produce the in-reactor blend occurs in the gas or slurryphase.
 30. The process of claim 27, wherein the macromonomer is made inthe same reactor as the in-reactor blend.
 31. The process of claim 27,where the process to produce the in-reactor blend comprises: (i)contacting at least one first monomer composition comprising ethylenewith a first catalyst capable of producing ethylene polymer having adensity of 0.920 g/cm³ or more and an M_(w) of 20,000 g/mol or more atthe selected polymerization conditions in a first polymerization stageunder conditions including a first temperature sufficient to produce theethylene-containing first polymer comprising at least 50% vinyl chainends; and (ii) contacting at least part of said first polymer with asecond monomer composition comprising ethylene and comonomer and with asecond catalyst capable of producing polymer having a density of 0.910g/cm³ or less or more in a second polymerization stage under conditionsincluding a second temperature sufficient to polymerize said secondmonomer composition to produce the ethylene-containing second polymer.32. The process of claim 31, wherein said first temperature is betweenabout 80° C. and about 140° C.
 33. The process of claim 31, wherein thecontacting (i) is conducted by slurry polymerization and/or thecontacting (ii) is conducted by solution polymerization.
 34. The processof claim 31, wherein each of the contacting (i) and contacting (ii) isconducted in the presence of a single site catalyst comprising at leastone metallocene catalyst and at least one activator.
 35. The process ofclaim 27, wherein the linear ethylene containing polymer has a CDBI of60% or more.
 36. The process of claim 27, wherein the linear ethylenecontaining polymer is an LLDPE or an HDPE.
 37. The process of claim 27,wherein the linear ethylene containing polymer has an M_(w) of 50,000g/mol or more, a g′ of 0.95 or more and an M_(w)/M_(n) of from greaterthan 1 to 10 and comprises from 50 mole % to 100 mole % ethylene andfrom 0 mole % to 50 mole % of C₂ to C₄₀ comonomer.
 38. The process ofclaim 27, wherein the linear ethylene containing polymer is a polymer ofan ethylene and at least one alpha olefin having 5 to 20 carbon atoms,where the linear ethylene containing polymer has a melt index (190°C./2.16 kg) of from 0.1 to 15 dg/min; a CDBI of at least 70%, a densityof from 0.910 to 0.930 g/cm³; a haze value of less than 20; a melt indexratio of from 35 to 80; an averaged modulus (M) of from 20 000 to 60 000psi and a relation between M and the dart impact strength in g/mil, DIS,complying with the formula:DIS≧0.8[100+exp(11.71−0.000268M+2.183×10⁻⁹M²)].
 39. The process of claim27, wherein the linear ethylene containing polymer has a density of0.940 g/cm³ or more.
 40. The composition of claim 7, wherein thecomposition has a decrease in the phase angle (δ) at a complex modulusof 10 kPa at 190° C. of at least 0.3° per wt % of the in-reactor polymerblend added relative to the linear ethylene containing polymer.
 41. Thecomposition of claim 40, wherein the composition is a homogenouspolymeric blend having an increase in the degree of shear thinning at190° C. of at least 0.002 per 1 wt % of the in-reactor polymer blendadded relative to the linear ethylene containing polymer.